CA2053594C - Communication system having isdn (integrated services digital network) signaling capability - Google Patents
Communication system having isdn (integrated services digital network) signaling capabilityInfo
- Publication number
- CA2053594C CA2053594C CA002053594A CA2053594A CA2053594C CA 2053594 C CA2053594 C CA 2053594C CA 002053594 A CA002053594 A CA 002053594A CA 2053594 A CA2053594 A CA 2053594A CA 2053594 C CA2053594 C CA 2053594C
- Authority
- CA
- Canada
- Prior art keywords
- control unit
- protocol message
- channel
- terminal
- information elements
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/04—Selecting arrangements for multiplex systems for time-division multiplexing
- H04Q11/0428—Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/40—Network security protocols
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/04—Selecting arrangements for multiplex systems for time-division multiplexing
- H04Q11/0428—Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals
- H04Q11/0435—Details
- H04Q11/0457—Connection protocols
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
- H04Q2213/216—Code signals; Framing (not synchronizing)
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
- H04Q2213/22—PBX
Abstract
A communications system operates compatibly with a public or private switching network using a Q.931 protocol for basic rate ISDN (Integrated Services Digital Network) communications. Communications between a control unit and station terminals of the system use a local protocol which is a modification of the Q.931 protocol. This local protocol includes one segment including the mandatory elements of the Q.931 protocol and a second segment derived by converting the optional elements of the Q.931 protocol into a local codeset which controls the user interface circuits at each station terminal. The local protocol enables call control between the control unit and each station terminal to be managed on a bearer channel basis while call control between the system and the network is managed on a call appearance basis using the standard Q.931 protocol. The local protocol provides for communicating line selection and feature activation commands from the terminal to the control unit, using simple button commands.
Description
COMMUNICATION SYSTEM HAVING ISDN (INTEGRATED
SERVICES DIGITAL NETWORK) SIGNALING CAPABILITY
Technical Field This invention relates to communication systems and, more particularly, to a communication system which operates over ISDN facilities.
Back~round of the Invention The Q.931 protocol has been accepted as the standard for ISDN (Integrated Services Digital Network) sign~ling channel communications over a central office loop to a subscriber location. In such an arrangement, a terminal at the subscriber's location generates user interface information (e.g., which features and buttons are used at the terminal) from call control information sent using the Q.931 protocol. Each terminal requires a relatively powerful processor, a collection of special sophisticated algorithms, a large random-access-memory (RAM) and a large read-only-memory (ROM) to generate the user interface information. Additionally, this call control complexity increasesproportionally with the number of line buttons on a station terminal. Unfortunately, these additional capabilities add significantly to the cost of station terminals. Moreover, to upgrade or add a feature to the terminals may require that changes be made to each terminal which adds significant terminal upgrade costs; since changes to the administrative data must be performed on a per terminal basis thereat.
What is desirable is a way to reduce terminal production cost and customer upgrade cost of the terminals while m:~int~ining their compatibility with the Q.931 protocol standard.
Summary of the Invention In accordance with the present invention, a communication system uses a Q.93 I protocol for basic rate ISDN communications with a public or a private switching network and uses a novel local protocol (NT2), a modified Q.931 protocol, for controlling communications between NT2 or Q.931-compatible station terminals and the control unit of the system. The NT2 local protocol enables call control between the control unit and station terminals to be managed on a bearer channel basis while network call control is managed on a call appearance or directory number basis. This reduces the cost of the user interface intensive voice terminals while still supporting network standard data devices.
~'' According to a feature of the present invention, the control unit processes or converts the Q.931 protocol message to a first group of information elements containing all mandatory Q.931 protocol message elements and a second group of information elements containing non-mandatory Q.931 protocol message elements. The second group of 5 elements controls the operation of user-interface devices (e.g., LED, display, alerter) at a station terminal. The first group of elements is used to establish a call connection between the control unit and any NT2 or Q.931-compatible station terminal.
According to another aspect of the present invention, the control unit manages call control on a call appearance basis and converts call control information received over 10 an external channel to a local protocol message having bearer channel format for communicating with a station terminal. The station terminal uses the local protocol message to control facility acquisition and to control user-interface devices. Another aspect of the present invention enables the system to identify station terminal types and to communicate NT2 protocol messages to NT2 station terminals and to communicate Q.931 15 protocol messages, including the optional elements, to Q.931 station terminals.
By m:~n~ging network-to-control unit call control on a call appearance basis at the control unit, and m:~n~ging control-unit-to terminal call control on a bearer channel basis, the processing and, therefor, the complexity of each terminal is dramatically reduced.
Moreover, because call control and a~1mini.~trative data stores are handled on a centralized 20 basis, essentially only the control unit of the system need be updated when features or facilities are added or changed in the system, or the system itself is upgraded, updated or reconfigured.
In accordance with one aspect of the invention there is provided a communication system arranged to receive ISDN (Integrated Services Digital Network) D
25 channel information in a Q.931 protocol message over a first ISDN communication channel, said system including a control unit connected to said first channel and connected over a communication facility, including one or more second communication channels, to at least one station terminal, said system further including at said control unit means for converting a received Q.931 protocol message which controls call connections over said first channel 30 using said D channel information, into a local protocol message for controlling communications with said at least one station terminal over said facility on a per second channel basis, said local protocol message controlling said at least one station terminal, said , . .
- 2a -local protocol message including a first group of information elements containing mandatory Q.931 protocol message information elements and a second group of information elements derived from a third group of information elements selected from one or more sets of information elements including 1) a first set of non-mandatory Q.931 protocol message information elements, and, 2) a second set of local information elements obtained from a data memory accessible by said control unit and at said at least one station terminal means for receiving said local protocol message and for controlling a calling state of at least one second channel of said at least one station terminal.
In accordance with another aspect of the invention there is provided a method of operating a communication system arranged to receive ISDN D channel information in a Q.931 protocol message over a first ISDN (Integrated Services Digital Network) communication channel, said system including a control unit connected to said first channel and connected over a communication facility, including one or more second communication channels, to at least one station terminal, said method comprising the steps of at said control unit converting a received Q.931 protocol message which controls call connections over said first channel using said D channel information, into a local protocol message, controlling communication with said at least one station terminal, over said facility on a per second channel basis, said local protocol message controlling said at least one station terminal, said local protocol message including a first group of information elements containing mandatory Q.931 protocol message information elements and a second group of information elements derived from a third group of information elements selected from one or more sets of information elements including 1) a first set of non-mandatory Q.931 protocol message information elements and 2) a second set of local information elements obtained from a data memory accessible by said control unit, and controlling a calling state of at least one second channel of said at least one station terminal.
Brief Description of the Drawing In the drawing, FIG. 1 is a block diagram of a communication system embodying the present invention;
FIG. 2 is a flow chart describing the operation of the control unit of the system in response to Q.931 protocol communications;
FIG. 3 illustrates converting of the Q.931 protocol SETUP message to the NT2 protocol SETUP message;
- ~ ' - 2b - 7 f~
FIG. 4 is a flow chart describing the operation of a Display Management Routine executed in the control unit;
FIG. 5 is a flow chart describing the operation of an Alerter/LED
management routine executed in the control unit;
5FIG. 6 illustrates a table indicting line-to-station assignments, station button/LED call mapping and station terminal type;
FIG. 7 illustrates a terminal-maintained user interface table;
FIG. 8 is a flow chart describing the operation of terminal in response to NT2 protocol communication;
FIG. 9 shows a comparison of the Q.931 protocol method of m~n~ging S call appearances, call control and the NT2 protocol method of m~n:~ging bearer channels for control; and FIG. 10 shows the various groups of Q.931 protocol messages used to control commllnic~ion connections.
General Description In the following description, elements of each figure have reference designations associated therewith, the most significant digit of which refers to the figure in which that element is located (e.g., 100 is located in FIG. 1).
Shown in FIG. 1 is an illustrative block diagram of a communic~tion system 102 useful in describing the operation of the present invention. The system 15 might typically be installed on the premises of a small business. The system includes Common Control Module or unit 10 which connects to one or more Switching Network (e.g., Central Office (CO)) lines 110 via Interface 111, and which connects via Interface 112 and one or more facilities 113 to, illustratively, one or more NT2-compatible terminals such as 105-106, Group 4 (G4) Fax Machine 107, 20 X.25 Terminal 108 and a Q.931-compatible terminal 109. Facilities 113 may be, for example, a point-to-point facility (not shown) or a multipoint passive bus, as shown in FIG. 1.
The general operation of the communication system shown in FIG. 1 is as follows. Control unit 103 establishes and controls all intercom and network 25 communic~ions. Control unit 103 includes Switch 114, Central Processor Unit (CPU) 115, Program Memory 116 and Data Memory 117. Program Memory 116 provides instructions to CPU 115 for Controlling Switch 114 and Interface Units 111 and 112 to enable the various operating features and fuslctions of the syste including those of the present invention. Data Memory 117 is utilized by CPU 11530 for storing and ~ccessing data associated with performing the various functions and features programmed in Program Memory 116. In a preferred embodiment CPU 115 is a microprocessor, Program Memory 116 is read-only-memory (ROM) and Data Memory 117 is random access memory (RAM). The Interface Circuits 111 and 112 may include well known circuitry such as ring detector, switching matrix, network 35 control, line circuits and other circuitry required by the system to establish, maintain and terminate communications.
~ 2053594 Each terminal e.g., 106, may, illustratively, be represented as including Line Interface 125, User Interface 126, a processor (CPU) 127, Program Memory 128 and Data Memory 129. Line Interface 125 includes the circuitry required to enable communications over facility 113. User interface representatively 5 includes the handset, display dial pad, line and feature buttons, associated LED
indicators, audio alerter and other well-known circuitry required to provide telephone commllnication at a terminal. The CPU 127 operates vendor program control using instructions stored in Program Memory 128 and data stored in Data Memory 129 which enables the terminal to provide the various commllnication 10 features and functions, including those of the present invention.
The communication system 102 shown in FIG. I is designed to provide basic rate ISDN communications with a Switching Network 100 (illustratively alsoreferred to hereinafter as a Central Office (CO)) using the Q.931 protocol. The ISDN Basic Rate Interface is typically two 64 Kbps bearer channels, known as the15 "B" channels, and one 16 Kbps signaling channel, also known as the "D" channel.
Like the Q.931 standard signaling protocol, the NT2 protocol described herein also applies to the D channel. The Q.931 protocol is defined by "The International Telegraph and Telephone Consultative ~ommittee, Digital Subscriber Si~n~lling System Number 1, Network Layer, Recommendation Q.931, Geneva, 1989."
20 The Q.931 protocol defines the standard method for handling multiple call appearances on a voice terminal (e.g., 120) connected directly to the network 100.
The Q.931 protocol handles multiple call appearances by managing one state machine for each call appearance (i.e., each Directory Number DN) at terminal 120.
This typically requires that terminal 120 m~int~in a state machine and call record for 25 each call appearance supported, and update a data instance (i.e., change in status) for each call offered and/or awarded to terminal 120.
The user interface for call appearance (or line) information is controlled by the terminal's processor and pLesents the user with a call-stale-related-userinterface condition (e.g., tone and or illumination) as determined by a complex call 30 evaluation algorithm. This call-related-user-interface information is derived from stored data instance information associated with each call appearance which is stored at terminal 120, and requires that terminal 120 maintain a complex evaluative algorithm to evaluate and update both the call control state machine and the user interface on the basis of both network and user input. Note that every Q.931 35 protocol-compatible terminal which connects to network 100 must contain the complex evaluative algorithm. Thus, each terminal 120 requires a relatively ~ 2053~91 powerful processor to process this complex evaluative algorithm. Moreover, when a new feature is changed or added at a terrninal, this algorithm may need to be changed.
In accordance with the present invention, control unit 103 of 5 communication system 102 provides Q.931 protocol-based ISDN
communications 101 with network 100 and provides centralized call control management on a network call appearance basis for all terminals 105, 106 of the system. Control unit 103 processes or converts the Q.931 protocol information 101 and uses a novel modified Q.93 1 protocol, referred to hereinafter as the NT2 local 10 protocol 104, to provide user interface communi(~tions with, and to simplify the call control interface to, Voice Terminals 105 and 106.
The NT2 protocol 104 is Q.931 compliant, where Q.931 compliant is defined as supporting, at a minimum, all messages used for call establishment and supporting all m~nd~tory information elements associated with those messages.
15 This architecture allows a reduction in the number of state machines needed at a terminal by managing bearer channel connection instances (i.e., maximum active call appearances=two for a basic rate ISDN channel) to the terminal rather than m~n~ging call appearances (equal to the number of incoming lines or directory numbers handled by the system). Thus, the user interface control, is separated from 20 call control and both are performed by control unit 103.
The control unit 103 m~int~ins data defining the current call and user interface states for all terminals that it serves. As new information is received from the network, (or as inforrnation is generated by activity initiated at other terminals behind the control unit), the control unit re-evaluates the user interface conditions at 25 all terminals logically related to that activity. This re-evaluation equates to an update of the appropriate control unit data tables, and execution of the algorithms of FIGS. 4 and 5. This architecture enables control unit 103 to send user interfacecommands to control call appearance inforrrlation at the terminal, thereby elimin~ing the need for the terminal to perform algorithmic evaluation of call 30 appearance inforrnation. Moreover, since there are a maximum of two bearer channels on a basic rate ISDN channel, each terminal need manage only a maximum of two state machines, independent of the number of call appearances that appear on the terminal.
FIG. 9 compares prior art Q.93 1 protocol call appearance 35 management 900 at terminal 120 with our NT2 method of bearer channel user interface management 910 at a system 102 terrninal (e.g., 105). According to our _ 205359~
invention, the Q.931 protocol call appearance management 900, which in prior artarrangements takes place at each system terminal, now takes place only at control unit 103, while the more simplified NT2 protocol bearer channel management 910 takes place at the system terminals 105 and 106. Thus, control unit 103 receives5 information in a Q.931 protocol format, performs all user interface algorithm execution on a call appearance basis 900 for all of its attached terminals, converts the Q.931 information into an NT2 protocol format, and offers the results to terminals 105 and 106 on a bearer channel basis 910.
Note that control unit 103 determines, using column 640 of FIG. 6, that the terminal identified by the DN (e.g., 109) is Q.931 type, not an NT2 type and the Information Flements of message 101 are retransmitted to the terminal 109 without alteration. This allows support of network standard (e.g., Q.931) terminals on the samebus 113.
The Q.931 SETUP message Information Elements (311, 313-317, 321) from the network are converted to the NT2 protocol elements 381-383 through a series of table lookups and evaluative processing. FIG. 5 outlines this process for the l,EDs and Alerting device, and FM. 4 similarly outlines the process for the Display. Control unit 103 sends user interface results to the terminals as a series of simple stimulus comm~nds which control known hardware entities in the terminals 105 and 106. In comparison, every instance of prior art terminal 120 will contain the user interface algorithms and a call control state machine data instance for every call appearance or directory number assigned to it. As a result, terminals 105 and 106 are much less complex, but provide, in combination with control unit 103, at least the same level of functionality as prior art terminal 120.
With reference to FIG. 3 we compare the Q.931 protocol to our novel NT2 protocol. For communications between control unit 103 and terminals 105 and 106, the NT2 protocol 104 provides more flexibility than the Q.931 protocol lûl, while conforming to the m~nd~tory components of that reference standard. The mandatory components of Q.931 include the messages, message 30 sequence, message contents and state machine behavior. The NT2 protocol, in accordance with the present invention, is intended for use at the "S" reference point in the ISDN model, and reflects the architectural differences between a central office and a customer premises switch. The benefits of this NT2 protocol architecture include:
20S~594 1. providing multiline capability Witll a reduced number of state machines required at each terminal, resulting in reduced terminal complexity.
SERVICES DIGITAL NETWORK) SIGNALING CAPABILITY
Technical Field This invention relates to communication systems and, more particularly, to a communication system which operates over ISDN facilities.
Back~round of the Invention The Q.931 protocol has been accepted as the standard for ISDN (Integrated Services Digital Network) sign~ling channel communications over a central office loop to a subscriber location. In such an arrangement, a terminal at the subscriber's location generates user interface information (e.g., which features and buttons are used at the terminal) from call control information sent using the Q.931 protocol. Each terminal requires a relatively powerful processor, a collection of special sophisticated algorithms, a large random-access-memory (RAM) and a large read-only-memory (ROM) to generate the user interface information. Additionally, this call control complexity increasesproportionally with the number of line buttons on a station terminal. Unfortunately, these additional capabilities add significantly to the cost of station terminals. Moreover, to upgrade or add a feature to the terminals may require that changes be made to each terminal which adds significant terminal upgrade costs; since changes to the administrative data must be performed on a per terminal basis thereat.
What is desirable is a way to reduce terminal production cost and customer upgrade cost of the terminals while m:~int~ining their compatibility with the Q.931 protocol standard.
Summary of the Invention In accordance with the present invention, a communication system uses a Q.93 I protocol for basic rate ISDN communications with a public or a private switching network and uses a novel local protocol (NT2), a modified Q.931 protocol, for controlling communications between NT2 or Q.931-compatible station terminals and the control unit of the system. The NT2 local protocol enables call control between the control unit and station terminals to be managed on a bearer channel basis while network call control is managed on a call appearance or directory number basis. This reduces the cost of the user interface intensive voice terminals while still supporting network standard data devices.
~'' According to a feature of the present invention, the control unit processes or converts the Q.931 protocol message to a first group of information elements containing all mandatory Q.931 protocol message elements and a second group of information elements containing non-mandatory Q.931 protocol message elements. The second group of 5 elements controls the operation of user-interface devices (e.g., LED, display, alerter) at a station terminal. The first group of elements is used to establish a call connection between the control unit and any NT2 or Q.931-compatible station terminal.
According to another aspect of the present invention, the control unit manages call control on a call appearance basis and converts call control information received over 10 an external channel to a local protocol message having bearer channel format for communicating with a station terminal. The station terminal uses the local protocol message to control facility acquisition and to control user-interface devices. Another aspect of the present invention enables the system to identify station terminal types and to communicate NT2 protocol messages to NT2 station terminals and to communicate Q.931 15 protocol messages, including the optional elements, to Q.931 station terminals.
By m:~n~ging network-to-control unit call control on a call appearance basis at the control unit, and m:~n~ging control-unit-to terminal call control on a bearer channel basis, the processing and, therefor, the complexity of each terminal is dramatically reduced.
Moreover, because call control and a~1mini.~trative data stores are handled on a centralized 20 basis, essentially only the control unit of the system need be updated when features or facilities are added or changed in the system, or the system itself is upgraded, updated or reconfigured.
In accordance with one aspect of the invention there is provided a communication system arranged to receive ISDN (Integrated Services Digital Network) D
25 channel information in a Q.931 protocol message over a first ISDN communication channel, said system including a control unit connected to said first channel and connected over a communication facility, including one or more second communication channels, to at least one station terminal, said system further including at said control unit means for converting a received Q.931 protocol message which controls call connections over said first channel 30 using said D channel information, into a local protocol message for controlling communications with said at least one station terminal over said facility on a per second channel basis, said local protocol message controlling said at least one station terminal, said , . .
- 2a -local protocol message including a first group of information elements containing mandatory Q.931 protocol message information elements and a second group of information elements derived from a third group of information elements selected from one or more sets of information elements including 1) a first set of non-mandatory Q.931 protocol message information elements, and, 2) a second set of local information elements obtained from a data memory accessible by said control unit and at said at least one station terminal means for receiving said local protocol message and for controlling a calling state of at least one second channel of said at least one station terminal.
In accordance with another aspect of the invention there is provided a method of operating a communication system arranged to receive ISDN D channel information in a Q.931 protocol message over a first ISDN (Integrated Services Digital Network) communication channel, said system including a control unit connected to said first channel and connected over a communication facility, including one or more second communication channels, to at least one station terminal, said method comprising the steps of at said control unit converting a received Q.931 protocol message which controls call connections over said first channel using said D channel information, into a local protocol message, controlling communication with said at least one station terminal, over said facility on a per second channel basis, said local protocol message controlling said at least one station terminal, said local protocol message including a first group of information elements containing mandatory Q.931 protocol message information elements and a second group of information elements derived from a third group of information elements selected from one or more sets of information elements including 1) a first set of non-mandatory Q.931 protocol message information elements and 2) a second set of local information elements obtained from a data memory accessible by said control unit, and controlling a calling state of at least one second channel of said at least one station terminal.
Brief Description of the Drawing In the drawing, FIG. 1 is a block diagram of a communication system embodying the present invention;
FIG. 2 is a flow chart describing the operation of the control unit of the system in response to Q.931 protocol communications;
FIG. 3 illustrates converting of the Q.931 protocol SETUP message to the NT2 protocol SETUP message;
- ~ ' - 2b - 7 f~
FIG. 4 is a flow chart describing the operation of a Display Management Routine executed in the control unit;
FIG. 5 is a flow chart describing the operation of an Alerter/LED
management routine executed in the control unit;
5FIG. 6 illustrates a table indicting line-to-station assignments, station button/LED call mapping and station terminal type;
FIG. 7 illustrates a terminal-maintained user interface table;
FIG. 8 is a flow chart describing the operation of terminal in response to NT2 protocol communication;
FIG. 9 shows a comparison of the Q.931 protocol method of m~n~ging S call appearances, call control and the NT2 protocol method of m~n:~ging bearer channels for control; and FIG. 10 shows the various groups of Q.931 protocol messages used to control commllnic~ion connections.
General Description In the following description, elements of each figure have reference designations associated therewith, the most significant digit of which refers to the figure in which that element is located (e.g., 100 is located in FIG. 1).
Shown in FIG. 1 is an illustrative block diagram of a communic~tion system 102 useful in describing the operation of the present invention. The system 15 might typically be installed on the premises of a small business. The system includes Common Control Module or unit 10 which connects to one or more Switching Network (e.g., Central Office (CO)) lines 110 via Interface 111, and which connects via Interface 112 and one or more facilities 113 to, illustratively, one or more NT2-compatible terminals such as 105-106, Group 4 (G4) Fax Machine 107, 20 X.25 Terminal 108 and a Q.931-compatible terminal 109. Facilities 113 may be, for example, a point-to-point facility (not shown) or a multipoint passive bus, as shown in FIG. 1.
The general operation of the communication system shown in FIG. 1 is as follows. Control unit 103 establishes and controls all intercom and network 25 communic~ions. Control unit 103 includes Switch 114, Central Processor Unit (CPU) 115, Program Memory 116 and Data Memory 117. Program Memory 116 provides instructions to CPU 115 for Controlling Switch 114 and Interface Units 111 and 112 to enable the various operating features and fuslctions of the syste including those of the present invention. Data Memory 117 is utilized by CPU 11530 for storing and ~ccessing data associated with performing the various functions and features programmed in Program Memory 116. In a preferred embodiment CPU 115 is a microprocessor, Program Memory 116 is read-only-memory (ROM) and Data Memory 117 is random access memory (RAM). The Interface Circuits 111 and 112 may include well known circuitry such as ring detector, switching matrix, network 35 control, line circuits and other circuitry required by the system to establish, maintain and terminate communications.
~ 2053594 Each terminal e.g., 106, may, illustratively, be represented as including Line Interface 125, User Interface 126, a processor (CPU) 127, Program Memory 128 and Data Memory 129. Line Interface 125 includes the circuitry required to enable communications over facility 113. User interface representatively 5 includes the handset, display dial pad, line and feature buttons, associated LED
indicators, audio alerter and other well-known circuitry required to provide telephone commllnication at a terminal. The CPU 127 operates vendor program control using instructions stored in Program Memory 128 and data stored in Data Memory 129 which enables the terminal to provide the various commllnication 10 features and functions, including those of the present invention.
The communication system 102 shown in FIG. I is designed to provide basic rate ISDN communications with a Switching Network 100 (illustratively alsoreferred to hereinafter as a Central Office (CO)) using the Q.931 protocol. The ISDN Basic Rate Interface is typically two 64 Kbps bearer channels, known as the15 "B" channels, and one 16 Kbps signaling channel, also known as the "D" channel.
Like the Q.931 standard signaling protocol, the NT2 protocol described herein also applies to the D channel. The Q.931 protocol is defined by "The International Telegraph and Telephone Consultative ~ommittee, Digital Subscriber Si~n~lling System Number 1, Network Layer, Recommendation Q.931, Geneva, 1989."
20 The Q.931 protocol defines the standard method for handling multiple call appearances on a voice terminal (e.g., 120) connected directly to the network 100.
The Q.931 protocol handles multiple call appearances by managing one state machine for each call appearance (i.e., each Directory Number DN) at terminal 120.
This typically requires that terminal 120 m~int~in a state machine and call record for 25 each call appearance supported, and update a data instance (i.e., change in status) for each call offered and/or awarded to terminal 120.
The user interface for call appearance (or line) information is controlled by the terminal's processor and pLesents the user with a call-stale-related-userinterface condition (e.g., tone and or illumination) as determined by a complex call 30 evaluation algorithm. This call-related-user-interface information is derived from stored data instance information associated with each call appearance which is stored at terminal 120, and requires that terminal 120 maintain a complex evaluative algorithm to evaluate and update both the call control state machine and the user interface on the basis of both network and user input. Note that every Q.931 35 protocol-compatible terminal which connects to network 100 must contain the complex evaluative algorithm. Thus, each terminal 120 requires a relatively ~ 2053~91 powerful processor to process this complex evaluative algorithm. Moreover, when a new feature is changed or added at a terrninal, this algorithm may need to be changed.
In accordance with the present invention, control unit 103 of 5 communication system 102 provides Q.931 protocol-based ISDN
communications 101 with network 100 and provides centralized call control management on a network call appearance basis for all terminals 105, 106 of the system. Control unit 103 processes or converts the Q.931 protocol information 101 and uses a novel modified Q.93 1 protocol, referred to hereinafter as the NT2 local 10 protocol 104, to provide user interface communi(~tions with, and to simplify the call control interface to, Voice Terminals 105 and 106.
The NT2 protocol 104 is Q.931 compliant, where Q.931 compliant is defined as supporting, at a minimum, all messages used for call establishment and supporting all m~nd~tory information elements associated with those messages.
15 This architecture allows a reduction in the number of state machines needed at a terminal by managing bearer channel connection instances (i.e., maximum active call appearances=two for a basic rate ISDN channel) to the terminal rather than m~n~ging call appearances (equal to the number of incoming lines or directory numbers handled by the system). Thus, the user interface control, is separated from 20 call control and both are performed by control unit 103.
The control unit 103 m~int~ins data defining the current call and user interface states for all terminals that it serves. As new information is received from the network, (or as inforrnation is generated by activity initiated at other terminals behind the control unit), the control unit re-evaluates the user interface conditions at 25 all terminals logically related to that activity. This re-evaluation equates to an update of the appropriate control unit data tables, and execution of the algorithms of FIGS. 4 and 5. This architecture enables control unit 103 to send user interfacecommands to control call appearance inforrrlation at the terminal, thereby elimin~ing the need for the terminal to perform algorithmic evaluation of call 30 appearance inforrnation. Moreover, since there are a maximum of two bearer channels on a basic rate ISDN channel, each terminal need manage only a maximum of two state machines, independent of the number of call appearances that appear on the terminal.
FIG. 9 compares prior art Q.93 1 protocol call appearance 35 management 900 at terminal 120 with our NT2 method of bearer channel user interface management 910 at a system 102 terrninal (e.g., 105). According to our _ 205359~
invention, the Q.931 protocol call appearance management 900, which in prior artarrangements takes place at each system terminal, now takes place only at control unit 103, while the more simplified NT2 protocol bearer channel management 910 takes place at the system terminals 105 and 106. Thus, control unit 103 receives5 information in a Q.931 protocol format, performs all user interface algorithm execution on a call appearance basis 900 for all of its attached terminals, converts the Q.931 information into an NT2 protocol format, and offers the results to terminals 105 and 106 on a bearer channel basis 910.
Note that control unit 103 determines, using column 640 of FIG. 6, that the terminal identified by the DN (e.g., 109) is Q.931 type, not an NT2 type and the Information Flements of message 101 are retransmitted to the terminal 109 without alteration. This allows support of network standard (e.g., Q.931) terminals on the samebus 113.
The Q.931 SETUP message Information Elements (311, 313-317, 321) from the network are converted to the NT2 protocol elements 381-383 through a series of table lookups and evaluative processing. FIG. 5 outlines this process for the l,EDs and Alerting device, and FM. 4 similarly outlines the process for the Display. Control unit 103 sends user interface results to the terminals as a series of simple stimulus comm~nds which control known hardware entities in the terminals 105 and 106. In comparison, every instance of prior art terminal 120 will contain the user interface algorithms and a call control state machine data instance for every call appearance or directory number assigned to it. As a result, terminals 105 and 106 are much less complex, but provide, in combination with control unit 103, at least the same level of functionality as prior art terminal 120.
With reference to FIG. 3 we compare the Q.931 protocol to our novel NT2 protocol. For communications between control unit 103 and terminals 105 and 106, the NT2 protocol 104 provides more flexibility than the Q.931 protocol lûl, while conforming to the m~nd~tory components of that reference standard. The mandatory components of Q.931 include the messages, message 30 sequence, message contents and state machine behavior. The NT2 protocol, in accordance with the present invention, is intended for use at the "S" reference point in the ISDN model, and reflects the architectural differences between a central office and a customer premises switch. The benefits of this NT2 protocol architecture include:
20S~594 1. providing multiline capability Witll a reduced number of state machines required at each terminal, resulting in reduced terminal complexity.
2. separating the user interface from the call control machine (control unit 103), thereby providing additional flexibility in call information to the user and reduced terminal complexity. In addition, the tçrmin~l need only support one method (Button ID) for communicating line selection and feature invocation.
Before proceeding with the det~il~ operating description of the present 10 invention, it should be recognized that the present invention may be utilized in a variety of other telephone communic~tion systems. Since such systems utilize a variety of hardware and programming techniques, no attempt is made to describe the hardware and programs used to control the comml-nic~tion system. However, the present invention must be incorporated into the overall structure of the system in 15 which it is used and should be tailored to mesh with other features and operations of the system. Thus, in order to avoid confusion and in order to enable those skilled in the art to practice the claimed invention, this specification will describe the operation of the present invention using the system block diagram of FIG. 1, the flow charts of FIGS. 2, 4, 5 and 8 and tables of FIGS., 6, 7 and 9.~0 Detailed Description With reference to F~G. 10, basic rate ISDN comml]nica~it)n uses Q.931 protocol messages divided into four groups including Call Establishment Messages 1011, Call Information Messages 1012, Call Clearing Messages 1013, and Miscellaneous Messages 1014. Each group includes one or more messages, e.g., the25 Call Establishment Message group includes a SETUP message described in detailherein. The SETUP message is described herein because it is the most complicatedin that it contains most of the information elements used in the Q.931 protocol, as shown by 301-321 of F~G. 3. The other messages of the different message classes use fewer information elements than shown by 301-321 of FIG. 3. More 30 importantly, the SETUP message contains all the optional, or non-m~ncl~tory, elements (311-317, 321) which are processed by the present invention into the Codeset 6 message set as described herein. Thus, the operation of the present invention during the communication of other than the SETUP messages proceeds in a consistent fashion with equivalent processing of the Q.931 optional information 35 elements (311-317, 321).
20~359~
Shown in FIG. 10 is an illustrative call establishment interaction between the control unit 103 and terminal 106 for a call initiated by termin~l 106.
This illustrative call setup basically describes the well-known Q.931 call setupprocedure, including the call establishment 1011, call information phase 1012, call S clearing 1013,andmiscellaneous 1014messages. Terminal 106goesoff-hookand sends a SETUP message 1001 and control unit 103 responds with a SETUP
ACKNOWLEDGE message 1002. The terminal 106 sends the remaining digits in INFORMATION messages 1003. When all digits are received, control unit sends CALL PROCEEDING 1004, ALERTING 1005 and then CONNECT 1006 to 10 terrninal 106. At this point, the call is cut-through and the user can comm~nic:~te to the far end. When the user at terminal 106 hangs-up, a DISCONNECT
message 1007 is sent to control unit 103. The control unit 1033 then sends a RELEASE message 1008 and terminal 106 sends RELEASE COMPLETE
message 1009. The control unit 10333 thereupon releases facility 113.
The following description of call processing at control unit 103 makes joint reference to FIGS. 1, 2 and 3. In step 200, which depicts control unit 103processing a message received from CO 100, control unit 103 validates the Protocol Discrimin~tor element 301 and does not process SETUP message 101 unless the Protocol Discriminator element 301 indicates a Q.931 message.
If the Protocol Discriminator element 301 received by the control unit is not Q.931, the control unit 103 may broadcast the entire message to all terrninals on the bus 113, as indicated by the DN 610. Q.931/NT2 terrninals will check the discriminator and not process the message since the discriminator is not appropriate.
Terminals, e.g.X.25 108, that recognize the discrimin~tor will operate properly.X.25 is an octet-oriented protocol, with a structure sirnilar to the Q.931 protocol.
However, it has a different protocol discrimin~tor element (301) than Q.931.
Therefore, X.25 devices can be supported by an NT2 control unit simply by transparently passing those messages with the X.25 discrimin~tor to the terrninals.
Note that the NT2 terrninal message processing algorithm will detect that an X.25 30 message is not an NT2 message, and take no action, thus allowing the X.25 terminal to operate properly on the same bus as a Q.931 or NT2 terminal. If the protocol discriminator element 301 is valid, then in step 202, the Call Reference element 302 is validated against currently-assigned references. If it is acceptable, processing continues. Otherwise, in step 203, an error message is sent to CO 100. In step 204, 35 the Message Type element 303, is then processed to determine if the message is appropriate to the current state of the call control state machine. If appropriate, the 2~53591 g processing continues; else an error message is declared back to CO 100 at step 205.
In step 206, control unit 103 checks if CO 100 has, optionally, included a Sending Complete element 304 in the Q.931 message to in(lic~te that all information needed to complete the call is present. Otherwise, in step 207, control unit 103 awaits5 further information. In step 208, the Bearer Capabilities information element 306 is decoded to deterrnine if the designated terminal, the terminal associated with call reference element 302, is capable of supporting the call type declared in element 306: if not, in step 209, the call is refused. Note that speech, e.g., terminal 106, or data, e.g., G4 fax machine 107, service is declared in Bearer 10 Capabilities information element 306. If data is asserted, then the High Layer and/or Low Layer Compatibility Information elements must be processed to deterrnine thedata coding format. This is used by the G4 Fax machine 107 to perform compatibility checking. The G4 Fax machine 107 is supported on the NT2 links by virtue of the fact that the control unit 103 passes through the Bearer Capabilities, 15 Low Layer Compatibility, and High Layer Compatibility elements on the NT2 station facility or bus 311. These elements are all that are required for channel service and endpoint decoding of the bearer channel contents. Thus, a G4 Fax, orany generalized data device, can be supported by the control unit 103. Note that, if terminal 106 includes a data capability, standard compatibility checking is 20 performed and the data service initi~t~.~l as appropriate. Thus, the terminal would then look at the bearer capabilities, high layer and low layer compatibility anddetermine if the call is a data or voice call.
In step 210, control unit 103 then checks the designated terminal channel use record to see if the channel declared in the Channel Identification 25 element 307 is acceptable; if not, in step 211, control unit 103 establishes a channel negotiation process with CO 100. In step 212, an optional Facilities element 308 is checked and, if present, in step 212, the requested functional supplementary services are invoked. Otherwise, in step 214, an optional Progress Indicator element 309 is checked and, if present, processed in step 215. In step 216, optional Network 30 Specific Facilities element 10 declaration is checked and, if present, processed in step 217. In step 218, if Display Information element 311 is contained in the SETUP
message 101, then control unit 103 evaluates whether or not to display the information at the designated terminal, and if so, processes the display information in step 250, to select the display area and to send the inforrnation to the designated 35 terminal for display as part of a Codeset 6 display message 381. In step 219, if the Keypad Information 312 is contained in the SETUP mess~~e 101, then in step 220, control unit 103 processes it, as appropriate to the context. In step 221, if Signal Information element 313 is present in the SETUP message 101, then in step 222 control unit 103 processes it as part of a Codeset 6 Audible Alert Control message 382. In step 223, control unit 103 evaluates the Feature Tn(lic:~tion 5 element 314 and, if present, processes the data for inclusion in Codeset 6 LED control message 383.
In step 225, control unit 103 decodes the optional Calling Party Number element 315 and Subaddress element 316 and, if present, then, in step 228, inserts them as part of display message 381. Display message 381, as later described, 10 enables a temminal to display the number of the caller or to relay the number to an application processor. In step 227, control unit 103 evaluates the optional Called Party Number element 317 and, if present, in step 228, inserts it as part of the LED
message 383 and display message 381. This LED display message 383, as later described, enables the receiving terminal, e.g., 105, to determine if it is the terminal 15 being called by the far-end caller. Using this Called Party Number element 317, control unit 103 can accept the call, and select the call appearance associated with the Called Party Number 317 as declared in message 101. If the Called Party Number element 317 is not valid, the call may be refused by control unit 103. Note, that this requires that control unit 103 have knowledge of the directory number(s) 20 (Called Party Number on an incoming call) for each terminal connected to it.
Table 600 of FIG. 6 provides such information. In step 229, if the User Information Element 229 is present, control unit 103 includes it in display message 381 which is sent to the user in step 230. If all checks are passed, then control unit 103 transfers an affirrnative response, in step 231, to the caller via CO 100; otherwise, a negative 25 response is returned in step 231.
If a positive acknowledgment in step 231 is returned by control unit 103 to central office 100, then control unit 103 proceeds to process the received information. As previously no~.ed ~bove, the receipt of ~.931 protccs~l inforrmation may include information used for temlinal displays, including the Facility 30 Information 308, Progress Indicator 309, Network Specific Facilities 310, Display Information 311, Feature Indication 314, Calling Party Number 315 and Subaddress 316, Called Party Number 317 and User-User Inforrmation 319. This infom~ation is then processed by the display management process routine shown inFIG 4. Control unit 103 executes the display management routine of FIG. 4 to 35 generate the display messages to be sent to terrninals 105 and 106.
With reference to step 401 of FIG. 4, the display management algorithm is performed. The display management algorithm determines the priority (i.e., 402, placement (i.e., 403) and attributes (i.e., 404) of the displayable information on the terminal display device. In step 402, the process determines if the particular 5 received information (e.g., Facility information 308) should be displayed at the terminal. If not, then Display process FIG. 4 returns control back to the main processing routine of FIG. 2. Assunling that the received information should be displayed, then in step 403 the cursor is located and in step 404 the presentation attribute is selected. The presentation attribute is selected by the control unit 10 algorithm and includes presentations such as blinking, reverse video, etc. Instep 405 the display message is formatted and in step 406 the display message is sent to the terminal. In step 407 it is determined whether more information is required to be sent. If so, control returns to step 402, otherwise control returns to the main processing routine of FIG. 2.
The receipt of Signal Information 313, in step 221, requires processing by the Alerter/LED routine shown in FIG. 5. The Signal Information may include the supervisory signaling information applicable to tones and alerting signals, ringing, etc. In step 501, the Alerter and LED activity algorithm is performed. This algorithm shows how the LED and Alerter conditions at the called terminal should20 be presented (e.g., flash LED, activate alerter). In step 502, the process determines if the terrninal LED should be updated. If updating is required, then in step 503 the LED is located using the table of FIG. 6 and, in step 504, the appropriate flash pattern is selected according to the call state for that call appearance. If no LED
updating is required or after LED updating is completed, process control moves to 25 step 505 where it is determined if the terminal alerter condition should be updated.
If so, then, in step 506, the alert pattern is selected according to the call state for that call appearance. If no alerter updating is required or after the alerter has been updated, process control moves to step 507 where i~ i3 derermined whether an alerter/LED message should be sent to the terminal. If not, control returns to the 30 main processor of FIG. 2, otherwise in step 508 the message is formatted. In step 509 the message is transferred to the called terminal and control returns to the main process of FIG. 2.
The above Alerter/LED processing of FIG. 5, required that control unit 103 utilize the terminal data table of FIG. 6 to select the button and LED pair 630 on 35 the eligible terminals that represent the Called Party Number 317 declared inmessage 101. The Alerter/LED processing also generated the flash pattern for ".!1=_ 20~3~9 1 the LED and an appropriate alerting tone selected according to a stored algorithm.
The control unit 103 transfers the display and Alerter/LED information to the target terminal(s) (105 and/or 106) using the NT2 SETUP message shown by 104 of FIG. 3 as described below.
In accordance with the present invention, after control unit 103 has received from CO 100 the information elements 301-321 of the Q.931 protocol SETUP message 101, it processes the information into a local NT2 protocol 104 for use in communications with terminals 105 and 106. The table 300 shown in FIG. 3 shows the mapping of the Q.931 protocol message 101 elements into our novel NT2 protocol message 104 elements. As illustrated, the NT2 protocol message 104 includes a first (m~nd~tory per Q.931) segment 370 and a second (local code set)segment 380. Control unit 103 sends a m~ncl~tory subset of the basic call control information elements (i.e., elements 301, 302, 303, 306 and 307) as part of a first segment 370 of NT2 protocol message. Control unit 103 translates or processes the optional subset of the Q.931 protocol message 101 information elements (i.e., 311, 313, 314, 315, 316, 317 and 321) into a second segment 380, called local codeset or Codeset 6, of the NT2 protocol message 104. The Codeset 6 elements 381-383 are generated by control unit 103 as a result of user interfaceprocessing previously described in FIGS. 4 and 5. As shown in FIG. 3 the 20 resulting NT2 protocol message 104 has a significantly-reduced information element set. The reduced information element set si~nific~ntly reduces the amount and complexity of the processing required at each terminal connected to the system.
At the control unit 103 the user interface processing, which maps Q.931 information elements 311, 313, 314, 315, 316, 317 and 321 into Codeset 6 25 elements 381, 382 and 383, may be implemented using algorithmic mapping. Thisrequires that control unit 103 maintain a data table which defines the relationship between directory numbers (DNs), column 610; system terminal, column 620; and button and LED call number at that terminal, column 630. In F~G. 6 each of the directory numbers, column 610, handled by the system may have an appearance at 30 more than one terminal. [Note that the data in this table is also used for faster management, as discussed below]. For example, DN 957 0000 is shown to have an appearance at the terminals identified as 1, 2, 3 and 4. At terminal 1, the button and LED number 1 is, illustratively, associated with DN 957 0000 while terminal number 4, illustratively, associates button/LED number 3 with DN 957 0000. Note,35 obviously, that a unique button/LED is assigned to each DN appearance at a terminal.
- 20~3~94 The simplified NT2 protocol command set is supported within the limits of the Q.931 protocol standard through use of the Locking Shift information element and procedure to shift to a local Codeset 6. As the NT2 Setup Message Tabulation 104 of FIG. 3 shows, the information elements in this NT2 protocol 5 message set are less in number and complexity than those in the Q.931 protocolmessage 101. Note that all mandatory information elements associated with basic Q.931 call control (301-303, 306) are supported by the NT2 protocol 104, but allothers (311, 313-317, 321) are processed by control unit 103 and issued to the terminal as commands (381-383) used to generate tones, activate LEDs, and manage10 the display. The difference between our NT2 protocol approach and the standard Q.931 protocol is that within the communication system 102, the complicated evaluative algorithms need exist only at control unit 103, rather than at each terminal 105, 106 of the system 102.
Thus, control unit 103 processes Q.931 Message 101 as depicted in the 1~ flow chart of FIG. 2 and formats an NT2 SETUP message 104 for the target terminal(s), based on the results of the execution of its evaluative algorithms for both call and user interface control. The flow chart of FIG. 8, discussed below, describes the message exchange between control unit 103 and the terminals 105 and/or 106.
Terminal processing of the NT2 protocol message 104 received from 20 control unit 103 is shown in FIG. 8. The step-by-step procedure is not repeated here but generally equivalent to that described above in FIG. 2. Thus, the terminal processing steps 800 through 805 are equivalent to the control unit 103 steps 200-205 previously described in FIG. 2 and the terminal processing steps 807-810 areequivalent to the control unit processing steps 208-210.
The user interface information contained in Codeset 6 is processed by the terminal in steps 811 through 816. In step 811 the LED control command, having content 701, is checked. If present, the terminal executes, in step 812, the command ard appropnately selects and activates the LED. In step 813 ~he Alerter control comrnand, having content 702, is checked. If present, the command is 30 executed, in step 814, and the appropriate tone is outputted by the Alerter. In step 815 the display control command is checked. If present, the display comm~nd, having content 703, is executed, in step 816, and the appropriate text is outputted on the terminal display. In step 817, the terminal returns an acknowledgment to theSETUP message to control unit 103.
205359~
Note, if a user at a terminal 105 or 106 activates a line or feature button thereat, a button command 704 is sent to the control unit 103 to identify the button and its state. If a user goes on-hook or off-hook, then an appropriate supervision message is sent to the control unit as per Q.93 1. These button and supervision 5 messages are sent as part of the Codeset 6 messages to the control unit 103 from the terminal, but including all mandatory components of Q.931.
Button ID's are used to identify Feature activation at the terrninal in the same fashion as line selection. The terminal sends only a button ID comm~nd to the control unit 103, which uses the data in its ~rlminis~ration table 600 (FIG. 6) to relate 10 the button to a feature (e.g., hold feature is button 4 on terminal 1.) The control unit then executes the feature.
This provides a single method for the terminal to process both line selection and feature activation operations, again simplifying the tennin~l while preserving full functionality for the user.
When a network service was indicated to control unit 103 by a terminal button depression, control unit 103 has the necessary information to translate that into a network message. This is based on the ~c~ministration data available to the control unit which relates buttons to lines or features/services. When control unit determines that a network service is being requested, e.g., the user wishes to place a 20 call, the control unit performs the obverse of the Q.931 to NT2 information element mapping described in FIG. 3. The mandatory elements are passed transparently to the network. The control unit can relate the line selected to a Directory Number as follows: when a user on a terminal depresses a button and the terminal advises the control unit of this event, the control unit knows which terminal sent the message, 25 and from its ~f~ministration data, which Directory Number is associated with a given Button ID. This allows the control unit to provide the assigned Directory Number to the network during call setup. Standard channel selection procedures are effected in the same manner as in the down linl~ direction, and the message is transferred to the network. Note that all mandatory and some optional information elements are thus30 supplied to the network from the control unit.
While the present invention has been described as applicable to the Q.93 1 protocol used with ISDN signaling, it is contemplated that the present invention can be readily adapted in a straightforward manner for use with other protocols which are similarly structured, e.g., Q.931 derivative protocols. Thus, the 35 present invention can be utili~d to supplement communication protocols which include a group of elements to control channel acquisition and a second group which 205359d provides additional information utilized by the device connected to the signaling channel.
What has been disclosed is merely illustrative of the present invention.
Other arrangements and methods can be implemented by those skilled in the art 5 without departing from the spirit and scope of the present invention.
Before proceeding with the det~il~ operating description of the present 10 invention, it should be recognized that the present invention may be utilized in a variety of other telephone communic~tion systems. Since such systems utilize a variety of hardware and programming techniques, no attempt is made to describe the hardware and programs used to control the comml-nic~tion system. However, the present invention must be incorporated into the overall structure of the system in 15 which it is used and should be tailored to mesh with other features and operations of the system. Thus, in order to avoid confusion and in order to enable those skilled in the art to practice the claimed invention, this specification will describe the operation of the present invention using the system block diagram of FIG. 1, the flow charts of FIGS. 2, 4, 5 and 8 and tables of FIGS., 6, 7 and 9.~0 Detailed Description With reference to F~G. 10, basic rate ISDN comml]nica~it)n uses Q.931 protocol messages divided into four groups including Call Establishment Messages 1011, Call Information Messages 1012, Call Clearing Messages 1013, and Miscellaneous Messages 1014. Each group includes one or more messages, e.g., the25 Call Establishment Message group includes a SETUP message described in detailherein. The SETUP message is described herein because it is the most complicatedin that it contains most of the information elements used in the Q.931 protocol, as shown by 301-321 of F~G. 3. The other messages of the different message classes use fewer information elements than shown by 301-321 of FIG. 3. More 30 importantly, the SETUP message contains all the optional, or non-m~ncl~tory, elements (311-317, 321) which are processed by the present invention into the Codeset 6 message set as described herein. Thus, the operation of the present invention during the communication of other than the SETUP messages proceeds in a consistent fashion with equivalent processing of the Q.931 optional information 35 elements (311-317, 321).
20~359~
Shown in FIG. 10 is an illustrative call establishment interaction between the control unit 103 and terminal 106 for a call initiated by termin~l 106.
This illustrative call setup basically describes the well-known Q.931 call setupprocedure, including the call establishment 1011, call information phase 1012, call S clearing 1013,andmiscellaneous 1014messages. Terminal 106goesoff-hookand sends a SETUP message 1001 and control unit 103 responds with a SETUP
ACKNOWLEDGE message 1002. The terminal 106 sends the remaining digits in INFORMATION messages 1003. When all digits are received, control unit sends CALL PROCEEDING 1004, ALERTING 1005 and then CONNECT 1006 to 10 terrninal 106. At this point, the call is cut-through and the user can comm~nic:~te to the far end. When the user at terminal 106 hangs-up, a DISCONNECT
message 1007 is sent to control unit 103. The control unit 1033 then sends a RELEASE message 1008 and terminal 106 sends RELEASE COMPLETE
message 1009. The control unit 10333 thereupon releases facility 113.
The following description of call processing at control unit 103 makes joint reference to FIGS. 1, 2 and 3. In step 200, which depicts control unit 103processing a message received from CO 100, control unit 103 validates the Protocol Discrimin~tor element 301 and does not process SETUP message 101 unless the Protocol Discriminator element 301 indicates a Q.931 message.
If the Protocol Discriminator element 301 received by the control unit is not Q.931, the control unit 103 may broadcast the entire message to all terrninals on the bus 113, as indicated by the DN 610. Q.931/NT2 terrninals will check the discriminator and not process the message since the discriminator is not appropriate.
Terminals, e.g.X.25 108, that recognize the discrimin~tor will operate properly.X.25 is an octet-oriented protocol, with a structure sirnilar to the Q.931 protocol.
However, it has a different protocol discrimin~tor element (301) than Q.931.
Therefore, X.25 devices can be supported by an NT2 control unit simply by transparently passing those messages with the X.25 discrimin~tor to the terrninals.
Note that the NT2 terrninal message processing algorithm will detect that an X.25 30 message is not an NT2 message, and take no action, thus allowing the X.25 terminal to operate properly on the same bus as a Q.931 or NT2 terminal. If the protocol discriminator element 301 is valid, then in step 202, the Call Reference element 302 is validated against currently-assigned references. If it is acceptable, processing continues. Otherwise, in step 203, an error message is sent to CO 100. In step 204, 35 the Message Type element 303, is then processed to determine if the message is appropriate to the current state of the call control state machine. If appropriate, the 2~53591 g processing continues; else an error message is declared back to CO 100 at step 205.
In step 206, control unit 103 checks if CO 100 has, optionally, included a Sending Complete element 304 in the Q.931 message to in(lic~te that all information needed to complete the call is present. Otherwise, in step 207, control unit 103 awaits5 further information. In step 208, the Bearer Capabilities information element 306 is decoded to deterrnine if the designated terminal, the terminal associated with call reference element 302, is capable of supporting the call type declared in element 306: if not, in step 209, the call is refused. Note that speech, e.g., terminal 106, or data, e.g., G4 fax machine 107, service is declared in Bearer 10 Capabilities information element 306. If data is asserted, then the High Layer and/or Low Layer Compatibility Information elements must be processed to deterrnine thedata coding format. This is used by the G4 Fax machine 107 to perform compatibility checking. The G4 Fax machine 107 is supported on the NT2 links by virtue of the fact that the control unit 103 passes through the Bearer Capabilities, 15 Low Layer Compatibility, and High Layer Compatibility elements on the NT2 station facility or bus 311. These elements are all that are required for channel service and endpoint decoding of the bearer channel contents. Thus, a G4 Fax, orany generalized data device, can be supported by the control unit 103. Note that, if terminal 106 includes a data capability, standard compatibility checking is 20 performed and the data service initi~t~.~l as appropriate. Thus, the terminal would then look at the bearer capabilities, high layer and low layer compatibility anddetermine if the call is a data or voice call.
In step 210, control unit 103 then checks the designated terminal channel use record to see if the channel declared in the Channel Identification 25 element 307 is acceptable; if not, in step 211, control unit 103 establishes a channel negotiation process with CO 100. In step 212, an optional Facilities element 308 is checked and, if present, in step 212, the requested functional supplementary services are invoked. Otherwise, in step 214, an optional Progress Indicator element 309 is checked and, if present, processed in step 215. In step 216, optional Network 30 Specific Facilities element 10 declaration is checked and, if present, processed in step 217. In step 218, if Display Information element 311 is contained in the SETUP
message 101, then control unit 103 evaluates whether or not to display the information at the designated terminal, and if so, processes the display information in step 250, to select the display area and to send the inforrnation to the designated 35 terminal for display as part of a Codeset 6 display message 381. In step 219, if the Keypad Information 312 is contained in the SETUP mess~~e 101, then in step 220, control unit 103 processes it, as appropriate to the context. In step 221, if Signal Information element 313 is present in the SETUP message 101, then in step 222 control unit 103 processes it as part of a Codeset 6 Audible Alert Control message 382. In step 223, control unit 103 evaluates the Feature Tn(lic:~tion 5 element 314 and, if present, processes the data for inclusion in Codeset 6 LED control message 383.
In step 225, control unit 103 decodes the optional Calling Party Number element 315 and Subaddress element 316 and, if present, then, in step 228, inserts them as part of display message 381. Display message 381, as later described, 10 enables a temminal to display the number of the caller or to relay the number to an application processor. In step 227, control unit 103 evaluates the optional Called Party Number element 317 and, if present, in step 228, inserts it as part of the LED
message 383 and display message 381. This LED display message 383, as later described, enables the receiving terminal, e.g., 105, to determine if it is the terminal 15 being called by the far-end caller. Using this Called Party Number element 317, control unit 103 can accept the call, and select the call appearance associated with the Called Party Number 317 as declared in message 101. If the Called Party Number element 317 is not valid, the call may be refused by control unit 103. Note, that this requires that control unit 103 have knowledge of the directory number(s) 20 (Called Party Number on an incoming call) for each terminal connected to it.
Table 600 of FIG. 6 provides such information. In step 229, if the User Information Element 229 is present, control unit 103 includes it in display message 381 which is sent to the user in step 230. If all checks are passed, then control unit 103 transfers an affirrnative response, in step 231, to the caller via CO 100; otherwise, a negative 25 response is returned in step 231.
If a positive acknowledgment in step 231 is returned by control unit 103 to central office 100, then control unit 103 proceeds to process the received information. As previously no~.ed ~bove, the receipt of ~.931 protccs~l inforrmation may include information used for temlinal displays, including the Facility 30 Information 308, Progress Indicator 309, Network Specific Facilities 310, Display Information 311, Feature Indication 314, Calling Party Number 315 and Subaddress 316, Called Party Number 317 and User-User Inforrmation 319. This infom~ation is then processed by the display management process routine shown inFIG 4. Control unit 103 executes the display management routine of FIG. 4 to 35 generate the display messages to be sent to terrninals 105 and 106.
With reference to step 401 of FIG. 4, the display management algorithm is performed. The display management algorithm determines the priority (i.e., 402, placement (i.e., 403) and attributes (i.e., 404) of the displayable information on the terminal display device. In step 402, the process determines if the particular 5 received information (e.g., Facility information 308) should be displayed at the terminal. If not, then Display process FIG. 4 returns control back to the main processing routine of FIG. 2. Assunling that the received information should be displayed, then in step 403 the cursor is located and in step 404 the presentation attribute is selected. The presentation attribute is selected by the control unit 10 algorithm and includes presentations such as blinking, reverse video, etc. Instep 405 the display message is formatted and in step 406 the display message is sent to the terminal. In step 407 it is determined whether more information is required to be sent. If so, control returns to step 402, otherwise control returns to the main processing routine of FIG. 2.
The receipt of Signal Information 313, in step 221, requires processing by the Alerter/LED routine shown in FIG. 5. The Signal Information may include the supervisory signaling information applicable to tones and alerting signals, ringing, etc. In step 501, the Alerter and LED activity algorithm is performed. This algorithm shows how the LED and Alerter conditions at the called terminal should20 be presented (e.g., flash LED, activate alerter). In step 502, the process determines if the terrninal LED should be updated. If updating is required, then in step 503 the LED is located using the table of FIG. 6 and, in step 504, the appropriate flash pattern is selected according to the call state for that call appearance. If no LED
updating is required or after LED updating is completed, process control moves to 25 step 505 where it is determined if the terminal alerter condition should be updated.
If so, then, in step 506, the alert pattern is selected according to the call state for that call appearance. If no alerter updating is required or after the alerter has been updated, process control moves to step 507 where i~ i3 derermined whether an alerter/LED message should be sent to the terminal. If not, control returns to the 30 main processor of FIG. 2, otherwise in step 508 the message is formatted. In step 509 the message is transferred to the called terminal and control returns to the main process of FIG. 2.
The above Alerter/LED processing of FIG. 5, required that control unit 103 utilize the terminal data table of FIG. 6 to select the button and LED pair 630 on 35 the eligible terminals that represent the Called Party Number 317 declared inmessage 101. The Alerter/LED processing also generated the flash pattern for ".!1=_ 20~3~9 1 the LED and an appropriate alerting tone selected according to a stored algorithm.
The control unit 103 transfers the display and Alerter/LED information to the target terminal(s) (105 and/or 106) using the NT2 SETUP message shown by 104 of FIG. 3 as described below.
In accordance with the present invention, after control unit 103 has received from CO 100 the information elements 301-321 of the Q.931 protocol SETUP message 101, it processes the information into a local NT2 protocol 104 for use in communications with terminals 105 and 106. The table 300 shown in FIG. 3 shows the mapping of the Q.931 protocol message 101 elements into our novel NT2 protocol message 104 elements. As illustrated, the NT2 protocol message 104 includes a first (m~nd~tory per Q.931) segment 370 and a second (local code set)segment 380. Control unit 103 sends a m~ncl~tory subset of the basic call control information elements (i.e., elements 301, 302, 303, 306 and 307) as part of a first segment 370 of NT2 protocol message. Control unit 103 translates or processes the optional subset of the Q.931 protocol message 101 information elements (i.e., 311, 313, 314, 315, 316, 317 and 321) into a second segment 380, called local codeset or Codeset 6, of the NT2 protocol message 104. The Codeset 6 elements 381-383 are generated by control unit 103 as a result of user interfaceprocessing previously described in FIGS. 4 and 5. As shown in FIG. 3 the 20 resulting NT2 protocol message 104 has a significantly-reduced information element set. The reduced information element set si~nific~ntly reduces the amount and complexity of the processing required at each terminal connected to the system.
At the control unit 103 the user interface processing, which maps Q.931 information elements 311, 313, 314, 315, 316, 317 and 321 into Codeset 6 25 elements 381, 382 and 383, may be implemented using algorithmic mapping. Thisrequires that control unit 103 maintain a data table which defines the relationship between directory numbers (DNs), column 610; system terminal, column 620; and button and LED call number at that terminal, column 630. In F~G. 6 each of the directory numbers, column 610, handled by the system may have an appearance at 30 more than one terminal. [Note that the data in this table is also used for faster management, as discussed below]. For example, DN 957 0000 is shown to have an appearance at the terminals identified as 1, 2, 3 and 4. At terminal 1, the button and LED number 1 is, illustratively, associated with DN 957 0000 while terminal number 4, illustratively, associates button/LED number 3 with DN 957 0000. Note,35 obviously, that a unique button/LED is assigned to each DN appearance at a terminal.
- 20~3~94 The simplified NT2 protocol command set is supported within the limits of the Q.931 protocol standard through use of the Locking Shift information element and procedure to shift to a local Codeset 6. As the NT2 Setup Message Tabulation 104 of FIG. 3 shows, the information elements in this NT2 protocol 5 message set are less in number and complexity than those in the Q.931 protocolmessage 101. Note that all mandatory information elements associated with basic Q.931 call control (301-303, 306) are supported by the NT2 protocol 104, but allothers (311, 313-317, 321) are processed by control unit 103 and issued to the terminal as commands (381-383) used to generate tones, activate LEDs, and manage10 the display. The difference between our NT2 protocol approach and the standard Q.931 protocol is that within the communication system 102, the complicated evaluative algorithms need exist only at control unit 103, rather than at each terminal 105, 106 of the system 102.
Thus, control unit 103 processes Q.931 Message 101 as depicted in the 1~ flow chart of FIG. 2 and formats an NT2 SETUP message 104 for the target terminal(s), based on the results of the execution of its evaluative algorithms for both call and user interface control. The flow chart of FIG. 8, discussed below, describes the message exchange between control unit 103 and the terminals 105 and/or 106.
Terminal processing of the NT2 protocol message 104 received from 20 control unit 103 is shown in FIG. 8. The step-by-step procedure is not repeated here but generally equivalent to that described above in FIG. 2. Thus, the terminal processing steps 800 through 805 are equivalent to the control unit 103 steps 200-205 previously described in FIG. 2 and the terminal processing steps 807-810 areequivalent to the control unit processing steps 208-210.
The user interface information contained in Codeset 6 is processed by the terminal in steps 811 through 816. In step 811 the LED control command, having content 701, is checked. If present, the terminal executes, in step 812, the command ard appropnately selects and activates the LED. In step 813 ~he Alerter control comrnand, having content 702, is checked. If present, the command is 30 executed, in step 814, and the appropriate tone is outputted by the Alerter. In step 815 the display control command is checked. If present, the display comm~nd, having content 703, is executed, in step 816, and the appropriate text is outputted on the terminal display. In step 817, the terminal returns an acknowledgment to theSETUP message to control unit 103.
205359~
Note, if a user at a terminal 105 or 106 activates a line or feature button thereat, a button command 704 is sent to the control unit 103 to identify the button and its state. If a user goes on-hook or off-hook, then an appropriate supervision message is sent to the control unit as per Q.93 1. These button and supervision 5 messages are sent as part of the Codeset 6 messages to the control unit 103 from the terminal, but including all mandatory components of Q.931.
Button ID's are used to identify Feature activation at the terrninal in the same fashion as line selection. The terminal sends only a button ID comm~nd to the control unit 103, which uses the data in its ~rlminis~ration table 600 (FIG. 6) to relate 10 the button to a feature (e.g., hold feature is button 4 on terminal 1.) The control unit then executes the feature.
This provides a single method for the terminal to process both line selection and feature activation operations, again simplifying the tennin~l while preserving full functionality for the user.
When a network service was indicated to control unit 103 by a terminal button depression, control unit 103 has the necessary information to translate that into a network message. This is based on the ~c~ministration data available to the control unit which relates buttons to lines or features/services. When control unit determines that a network service is being requested, e.g., the user wishes to place a 20 call, the control unit performs the obverse of the Q.931 to NT2 information element mapping described in FIG. 3. The mandatory elements are passed transparently to the network. The control unit can relate the line selected to a Directory Number as follows: when a user on a terminal depresses a button and the terminal advises the control unit of this event, the control unit knows which terminal sent the message, 25 and from its ~f~ministration data, which Directory Number is associated with a given Button ID. This allows the control unit to provide the assigned Directory Number to the network during call setup. Standard channel selection procedures are effected in the same manner as in the down linl~ direction, and the message is transferred to the network. Note that all mandatory and some optional information elements are thus30 supplied to the network from the control unit.
While the present invention has been described as applicable to the Q.93 1 protocol used with ISDN signaling, it is contemplated that the present invention can be readily adapted in a straightforward manner for use with other protocols which are similarly structured, e.g., Q.931 derivative protocols. Thus, the 35 present invention can be utili~d to supplement communication protocols which include a group of elements to control channel acquisition and a second group which 205359d provides additional information utilized by the device connected to the signaling channel.
What has been disclosed is merely illustrative of the present invention.
Other arrangements and methods can be implemented by those skilled in the art 5 without departing from the spirit and scope of the present invention.
Claims (18)
1. A communication system arranged to receive ISDN D channel information in a Q.931 protocol message over a first ISDN communication channel, said systemincluding a control unit connected to said first channel and connected over a communication facility, including one or more second communication channels, to at least one station terminal, said system further including:
at said control unit;
means for converting a received Q.931 protocol message which controls call connections over said first channel using said D channel information, into a local protocol message for controlling communications with said at least one station terminal over said facility on a per second channel basis, said local protocol message controlling said at least one station terminal, said local protocol message including;
a first group of information elements containing mandatory Q.931 protocol message information elements; and a second group of information elements derived from a third group of informationelements selected from one or more sets of information elements including, 1) a first set of non-mandatory Q.931 protocol message information elements, and 2) a second set of local information elements obtained from a data memory accessible by said control unit; and at said at least one station terminal;
means for receiving said local protocol message and for controlling a calling state of at least one second channel of said at least one station terminal.
at said control unit;
means for converting a received Q.931 protocol message which controls call connections over said first channel using said D channel information, into a local protocol message for controlling communications with said at least one station terminal over said facility on a per second channel basis, said local protocol message controlling said at least one station terminal, said local protocol message including;
a first group of information elements containing mandatory Q.931 protocol message information elements; and a second group of information elements derived from a third group of informationelements selected from one or more sets of information elements including, 1) a first set of non-mandatory Q.931 protocol message information elements, and 2) a second set of local information elements obtained from a data memory accessible by said control unit; and at said at least one station terminal;
means for receiving said local protocol message and for controlling a calling state of at least one second channel of said at least one station terminal.
2. The system of claim 1, wherein said local protocol message identifies calls on a bearer channel connection basis.
3. The system of claim 1, wherein the local protocol message enables said at least one station terminal to manage line selection and feature invocation by sending button identification signals in said local protocol message sent from said at least one station terminal to said control unit.
4. The system of claim 1, wherein said facility is a multipoint passive bus and wherein said first group of information elements includes the mandatory elements of said Q.931 protocol message for supporting Q.931 compatible devices that require a connection on said multipoint passive bus.
5. The system of claim 1, wherein said facility includes a separate point-to-point facility to connect to each of said at least one station terminal to said control unit.
6. The system of claim 1, wherein said at least one station terminal includes means responsive to said first group of information elements for establishing a call connection between said control unit and said at least one station terminal.
7. The system of claim 1, wherein said at least one station terminal includes means for controlling user interactions with said station terminal, via a user-interface device, using said second group of control information elements.
8. The system of claim 7, wherein the user-interface device is an LED device.
9. The system of claim 7, wherein the user-interface device is a display device.
10. The system of claim 7, wherein the user-interface device is an alerting device.
11. The system of claim 1, wherein said local protocol message enables a Q.931 compatible terminal connected over a facility to said control unit to establish a communication connection therewith.
12. The system of claim 1, further including a second station terminal connectedover said facility to said control unit, said second station terminal communicating with said control unit using Q.931 protocol messages; and said control unit further including;
means for determining terminal type from a terminal data table and for communicating said Q.931 protocol messages over said facility when said second terminal is determined to be a Q.931 terminal type.
means for determining terminal type from a terminal data table and for communicating said Q.931 protocol messages over said facility when said second terminal is determined to be a Q.931 terminal type.
13. A control unit for use in a communication system including at least one station terminal connected over a communication facility to said control unit, said control unit also connected to an external ISDN communication channel, said control unitcomprising:
means for receiving ISDN D channel call control information in a Q.931 control protocol message over said external communication channel;
means for converting a received Q.931 protocol message which controls call connections over said first channel using said D channel information, into a local protocol message for controlling communications with said at least one station terminal over said facility on a per second channel basis, said local protocol message controlling said at least one station terminal, said local protocol message including;
a first group of information elements containing unprocessed mandatory Q.931 protocol message information elements for establishing a call connection between said control unit and said at least one station terminal; and a second group of information elements derived from a third group of informationelements selected from one or more sets of information elements including, 1) a first set of non-mandatory Q.931 protocol message information elements, and 2) a second set of local information elements obtained from a data memory accessible by said control unit; and means for sending said local protocol message over said facility to said at least one station terminal.
means for receiving ISDN D channel call control information in a Q.931 control protocol message over said external communication channel;
means for converting a received Q.931 protocol message which controls call connections over said first channel using said D channel information, into a local protocol message for controlling communications with said at least one station terminal over said facility on a per second channel basis, said local protocol message controlling said at least one station terminal, said local protocol message including;
a first group of information elements containing unprocessed mandatory Q.931 protocol message information elements for establishing a call connection between said control unit and said at least one station terminal; and a second group of information elements derived from a third group of informationelements selected from one or more sets of information elements including, 1) a first set of non-mandatory Q.931 protocol message information elements, and 2) a second set of local information elements obtained from a data memory accessible by said control unit; and means for sending said local protocol message over said facility to said at least one station terminal.
14. The control unit of claim 13, wherein said local protocol message identifiescalls on a bearer channel connection basis.
15. The control unit of claim 13, wherein the local protocol message enables said control unit to manage line selection and feature invocation by receiving button identification signals in a local protocol message received over said facility.
16. The control unit of claim 13, further including:
means for determining terminal type from a terminal data table and for communicating said Q.931 protocol messages over said facility when said terminal is determined to be a Q.931 terminal.
means for determining terminal type from a terminal data table and for communicating said Q.931 protocol messages over said facility when said terminal is determined to be a Q.931 terminal.
17. A method of operating a communication system arranged to receive ISDN D
channel information in a Q.931 protocol message over a first ISDN communication channel, said system including a control unit connected to said first channel and connected over a communication facility, including one or more second communication channels, to at least one station terminal, said method characterized by the steps of:
at said control unit;
converting a received Q.931 protocol message which controls call connections over a first channel using said D channel information, into a local protocol;
controlling communications with said at least one station terminal, over said facility on a per second channel basis, said local protocol message controlling said at least one station terminal, said local protocol message including;
a first group of information elements containing unprocessed mandatory Q.931 protocol message information elements for Q.931 complaint channel selection; anda second group of information elements derived from a third group of informationelements selected from one or more sets of information elements including, 1) a first set of non-mandatory Q.931 protocol message information elements, and 2) a second set of local information elements obtained from a data memory accessible by said control unit; and controlling a calling state of at least one second channel of said at least one station terminal.
channel information in a Q.931 protocol message over a first ISDN communication channel, said system including a control unit connected to said first channel and connected over a communication facility, including one or more second communication channels, to at least one station terminal, said method characterized by the steps of:
at said control unit;
converting a received Q.931 protocol message which controls call connections over a first channel using said D channel information, into a local protocol;
controlling communications with said at least one station terminal, over said facility on a per second channel basis, said local protocol message controlling said at least one station terminal, said local protocol message including;
a first group of information elements containing unprocessed mandatory Q.931 protocol message information elements for Q.931 complaint channel selection; anda second group of information elements derived from a third group of informationelements selected from one or more sets of information elements including, 1) a first set of non-mandatory Q.931 protocol message information elements, and 2) a second set of local information elements obtained from a data memory accessible by said control unit; and controlling a calling state of at least one second channel of said at least one station terminal.
18. A method of operating a control unit for use in a communication system including at least one station terminal connected over a communication facility to said control unit, said control unit also connected to an external ISDN communication channel, the method comprising the steps of:
receiving ISDN D channel call control information in a Q.931 control protocol message over said external communication channel;
converting a received Q.931 protocol message which controls call connections over a first channel using said D channel information, into a local protocol message for controlling communications with said at least one station terminal over said facility on a per second channel basis, said local protocol message controlling said at least one station terminal, said local protocol message including;
a first group of information elements containing mandatory Q.931 protocol message information elements for controlling a call setup at said at least one station terminal; and a second group of information elements derived from a third group of informationelements selected from one or more sets of information elements including, 1) a first set of non-mandatory Q.931 protocol message information elements, and 2) a second set of local information elements obtained from a data memory accessible by said control unit; and sending said local protocol message over said facility to said at least one station terminal.
receiving ISDN D channel call control information in a Q.931 control protocol message over said external communication channel;
converting a received Q.931 protocol message which controls call connections over a first channel using said D channel information, into a local protocol message for controlling communications with said at least one station terminal over said facility on a per second channel basis, said local protocol message controlling said at least one station terminal, said local protocol message including;
a first group of information elements containing mandatory Q.931 protocol message information elements for controlling a call setup at said at least one station terminal; and a second group of information elements derived from a third group of informationelements selected from one or more sets of information elements including, 1) a first set of non-mandatory Q.931 protocol message information elements, and 2) a second set of local information elements obtained from a data memory accessible by said control unit; and sending said local protocol message over said facility to said at least one station terminal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002173374A CA2173374C (en) | 1990-11-21 | 1991-10-16 | Communication system having isdn (integrated services digital network) signaling capability |
Applications Claiming Priority (2)
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| US07/616,961 US5278972A (en) | 1990-11-21 | 1990-11-21 | Communication system for converting ISDN signaling protocol between local and public network having first group of mandatory elements and second group of non-mandatory elements |
| US616,961 | 1990-11-21 |
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| CA002173374A Division CA2173374C (en) | 1990-11-21 | 1991-10-16 | Communication system having isdn (integrated services digital network) signaling capability |
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| US4999771A (en) * | 1987-08-31 | 1991-03-12 | Control Data Corporation | Communications network |
| US5063494A (en) * | 1989-04-12 | 1991-11-05 | Unisys Corporation | Programmable data communications controller |
| CA1331215C (en) * | 1989-09-29 | 1994-08-02 | Andrew Lazlo Aczel | Resource-decoupled architecture for a telecommunications switching system |
| US5164981A (en) * | 1990-06-04 | 1992-11-17 | Davox | Voice response system with automated data transfer |
| US5134644A (en) * | 1990-08-17 | 1992-07-28 | Senses International | Data communication device |
-
1990
- 1990-11-21 US US07/616,961 patent/US5278972A/en not_active Expired - Lifetime
-
1991
- 1991-10-16 CA CA002053594A patent/CA2053594C/en not_active Expired - Fee Related
- 1991-11-12 EP EP91310416A patent/EP0487234B1/en not_active Expired - Lifetime
- 1991-11-12 DE DE69126402T patent/DE69126402T2/en not_active Expired - Fee Related
- 1991-11-18 KR KR1019910020468A patent/KR0126461B1/en not_active IP Right Cessation
- 1991-11-20 JP JP3329679A patent/JPH0720153B2/en not_active Expired - Fee Related
-
1998
- 1998-02-16 HK HK98101198A patent/HK1002137A1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| EP0487234B1 (en) | 1997-06-04 |
| KR0126461B1 (en) | 1997-12-26 |
| CA2053594A1 (en) | 1992-05-22 |
| JPH0720153B2 (en) | 1995-03-06 |
| KR920011141A (en) | 1992-06-27 |
| EP0487234A3 (en) | 1993-05-05 |
| JPH04290341A (en) | 1992-10-14 |
| DE69126402D1 (en) | 1997-07-10 |
| HK1002137A1 (en) | 1998-07-31 |
| EP0487234A2 (en) | 1992-05-27 |
| US5278972A (en) | 1994-01-11 |
| DE69126402T2 (en) | 1997-12-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |