CA2146652A1

CA2146652A1 - Private branch exchange system and methods for operating same

Info

Publication number: CA2146652A1
Application number: CA002146652A
Authority: CA
Inventors: William T. Matern; Amy K. Leach
Original assignee: Individual
Current assignee: Newton Communications Inc
Priority date: 1992-10-08
Filing date: 1993-10-07
Publication date: 1994-04-28
Also published as: AU5324894A; US5592473A; WO1994009603A1; US5313459A

Abstract

A digital private branch exchange system (10, 10') and methods of operating same are provided. A system (10, 10') is cap-able of providing improved and integrated conference calling, voice mail, music on hold, call forwarding features, without being subject to the typical problems associated with the prior art.

Description

~ 0 94/09603 2 ~ ~ 6 ~ 5 2 PC~r/US93/09609 4 Background of the Invention Field of the Invention 6 The present application is, in part, a continuation of 7 copending application Serial No. 07/958,310 filed October 8 8, 1992.
9 The present invention is generally related to communication systems and, more specifically, to private 11 branch exchange systems including key systems, and methods 12 for operating same.
13 Brief Description of the Pertinent Prior Art 14 A modern private branch exchange (PBX) system, in addition to facilitating communication among its lines and 16 extensions must be capable of providing a number of 17 special user services. For example, a PBX system must be 18 capable of generating and routing, to each line and 19 extension, a variety of standard and non-standard informational and supervisory tonal signals, such as, dial 21 tone, audible ringing signal, etc., to provide each user 22 with individualized call-status information. Furthermore, 23 it is often desirable to supply special tonal signals, 24 either with or without verbal messages, to assist callers in using the PBX and/or to provide information concerning 26 their use thereof. Also, recently, it has also become 27 desirable to provide such features as "music on hold", 28 "voice mail", "station message detail recording" (SMDR), 29 and "call forwarding." Also, given the needs of the modern office, the PBX system must have a conferencing 31 feature for temporarily connecting a plurality of PBX
32 system lines and/or extensions- so that they may converse 33 and/or exchange data simultaneously.
34 Conventional PBX systems exist which are capable of providing certain of the foregoing features. Typically, 36 however, in order to be able to provide each of these W O 94/09603 2 1 ~ 6 ~ ~ ~ PC~r/US93/0960 ~

1 special and particularly desirable features, conventional 2 PBX systems incorporate application specific, dedicated 3 hardware. For example, separate custom-made hardware 4 modules are used in conventional systems to facilitate conference calling, generate tonal information signals and 6 to distribute these signals to the plurality users 7 (usually by means of a separate bus network), and to store 8 and retrieve data (including informational and voice 9 messages in "voice mail" systems).
A number of disadvantages result from the use of 11 application specific circuitry to provide special user 12 services in conventional systems. For example, the custom 13 hardware used to generate tonal signals is only capable of 14 producing a limited number of frequencies and amplitudes (power levels), and therefore, the tones which may be 16 provided are invariably fixed depending on the specific 17 type of custom hardware used within the system. This is 18 especially unfortunate given the nature of today's 19 telecommunications standards and global economy.
Signalling frequency and amplitude standards differ from 21 country to country, necessitating modifications of tonal 22 signals to conform to each country's communications 23 standards. Also, in order to effect these changes, 24 significant and costly modifications must be made to the system's hardware, in order for the PBX system to be able 26 to conform to these different telecommunication standards.
27 In certain cases, the required modifications may be so 28 extensive as to necessitate substituting an entirely 29 different PBX system for the one currently in use.
Serious signal attenuation problems also plague 31 conventional systems. For example, in a conventional 32 system, the custom hardware used to generate tonal signals 33 is connected, in parallel, to each of the output ports 34 (via a distribution network). This arrangement causes the signal power distributed to each of the output ports to 36 decrease proportionately along with the addition of each ~ 0 94/09603 2 1 ~ 6 6 5 2 PC~r/US93/09609 1 new output port and/or output line, necessitating the use 2 of amplification and/or signal repeater circuitry 3 distributed throughout the system.
4 Further problems may result when "voice mail" features are incorporated into a typical PBX system.
6 Conventionally, the circuitry used to provide "voice mail"
7 features comprise separate and distinct systems from the 8 main PBX system. These separate systems are interfaced to 9 the main PBX system via analog telephone lines and communicate with each other using one or more 11 predetermined, standard signaling protocols (which may be, 12 for example, combinations of hook-flashes, dual tone 13 multiple frequency signals, or other protocols). Thus, 14 each of the systems (the "voice mail" and main PBX
systems) must be provisioned with necessary hardware to 16 communicate using combinations of appropriate timing 17 instructions and/or other protocol commands so as to 18 synchronize their operations. This can result in the 19 profound disadvantage that, if synchronization is lost between the separate systems, the overall PBX system will 21 no longer function properly. Additionally, during 22 initialization, the user of conventional "voice mail"
23 systems may experience long periods of delay, since the 24 communications protocol must be established and initialized among the separate systems prior to the 26 beginning of data transfer to the voice mail system.
27 Moreover, depending upon the amount of time required to 28 initialize the voice mail and main PBX systems prior to 29 transfer of data between the two systems, it may be impossible to implement a voice mail feature having 31 meaningful utility. Also, since each of the systems is 32 distinct from the other systems, each system must have its 33 own individual control circuitry and 34 administrative/control information data bases, and therefore, must be individually administered and 36 maintained. These problems (the requirement for main PBX

W094/09603 1 PCT/US93/0960 ~
2146652 ~4~

1 and voice mail system synchronization, and separate, 2 distinct administrative/control means for each system) 3 serve to significantly increase the overall system~s 4 maintenance costs, required administrative down-time, and electronic complexity.
6 Moreover, PBX "call forwarding" features currently 7 available are quite limited in their capabilities.
8 Typical "call forwarding" schemes merely re-route, after a 9 predetermined amount of time, an incoming call from one line or extension of the PBX system to another 11 predetermined extension. This can result in, inter alia, 12 two major disadvantages. First, inconveniently, if the 13 second extension is not answered, then, the caller must 14 attempt to contact the desired party later by making a second call to the PBX system. Second, since a 16 conventional PBX system's "call forwarding" circuitry may 17 only redirect an incoming call from one PBX extension to 18 another extension within the system, and not to an outside 19 line remote from the system, individuals who usually would be at a given PBX extension (for example, in the 21 workplace), but are currently at a location remote 22 therefrom (for example, at home or commuting) cannot be 23 reached by the PBX system.
24 Finally, given the complexity and large number of functions provided to callers by modern PBX systems (and 26 the resulting complexity of instruction manuals describing 27 these PBX systems), it has become necessary for PBX
28 systems to automatically give callers special signals 29 and/or messages to assist and/or prompt them in using and administering the system. Conventional PBX systems that 31 provide such features do so by (1) providing LCD monitors 32 and/or video displays to permit the system to display on-33 line "help" and other information to users, (2) employing 34 a pre-recorded message delivery system substantially identical to conventional "voice mail" systems to transmit 36 verbal information to users to "walk" them through ~ 9~/09603 2 1 ~ ~ 6 ~ 2 PCT/US93/09609 -5- ~

1 accessing particular functions of the separate voice mail 2 system, and/or (3) using special tone generating 3 circuitry. None of these conventional techniques, 4 however, is without significant drawbacks.
LCD and/or video monitors are expensive, and the on-6 line help features of PBX systems which use them cannot be 7 accessed from locations remote from the PBX (e.g. home 8 offices) absent provision of specialized electronics for 9 that purpose. Also, typical pre-recorded messages are quite limited and are distributed via separate and 11 distinct record/playback systems similar to conventional 12 "voice mail" systems. Thus, the problems and drawbacks 13 associated with conventional messaging systems are similar 14 (if not identical) to those of conventional "voice mail"
subsystems. For example, one such problem is derived from 16 the fact that significant periods of delay may be 17 experienced during initialization of the main PBX and 18 messaging systems. This delay is inconvenient and reduces 19 the utility of the overall system.
Examples of conventional communications and/or private 21 branch exchange systems include: U.S. Patent No.
22 4,215,247, issued to Lambert; U.S. Patent No. 4,280,216, 23 issued to Zeitrag; U.S. Patent No. 4,371,752, issued to 24 Matthews et al.; U.S. Patent No. 4,566,096, issued to Sarson et al; U.S. Patent No. 4,701,948, issued to Molnar;
26 U.S. Patent No. 4,964,157, issued to Aoshima; U.S. Patent 27 No. 4,480,330, issued to Magnusson et al; and U.S. Patent 28 No. 4,460,807 issued to Kerr et al.
29 Objects Of The Invention It is a general objective of the present invention to 31 provide a PBX system that overcomes the problems and 32 disadvantages associated with conventional PBX systems.
33 More specifically, it is an object of the present 34 invention to provide a digital private branch exchange system having integrated "conference callingl', "voice 36 mail," "music on hold," "call forwarding," and on-line W O 94/09603 2 1 4 ~ 6 5 2 -6- PC~r/US93/0960 1 system information delivery capabilities.
2 Further objectives of the present invention include 3 providing a PBX system wherein call-status tones may be 4 easily and inexpensively modified and wherein attenuation of supervisory signals distributed to the individual 6 exchanges is substantially eliminated.
7 Summary Of The Invention 8 Accordingly, in one preferred embodiment of one aspect 9 of the present invention, a digital PBX system is provided comprising a plurality of input and output ports. At 11 least one input port and output port are recursively 12 connected so as to provide at least one feedback receiving 13 and transmitting port connected by a feedback path or bus 14 means. Each of the plurality of input and output ports, including the feedback receiving and transmitting ports, 16 are capable of transmitting at least one digitally encoded 17 (for example, in pulse code modulation format) time 18 division multiplexed (TDM) signal in at least one 19 respective time slot. ~ontrol means is provided for controlling the PBX system, generating supervisory data 21 corresponding to a plurality of supervisory tones, and for 22 facilitating other functions of the system. Switching 23 means is also provided for interconnecting any of the time 24 slots of the ports. The supervisory data generated by the control means may be supplied to the feedback bus means so 2 6 as to provide, in respective time slots, the supervisory 27 data corresponding to the supervisory tones to any of the 28 time slots of the ports, as desired. Additionally, data 29 storage means may be provided, according to this aspect of the instant invention, for storing and retrieving 31 supervisory data (generated by the control means), voice 32 mail data, and digitized verbal instructional messages.
33 In another embodiment of this aspect of the present 34 invention, a PBX system is provided that is essentially identical to the previously described embodiment, except 36 that the feedback path is eliminated. The control means 094/09603 2~ 4 6652 PCT/US93/09609 1 generates and transmits supervisory signals to the switch 2 means. By appropriately controlling operation of the 3 switch means, the supervisory data (and/or other data, 4 such as voice mail and informational data) supplied to the switch means may be routed by the switch means to any of 6 the time slots of the ports. Just as in the 7 aforedescribed embodiment, data storage means may be 8 provided for storing and retrieving supervisory data 9 generated by the control means, voice mail data, and digitized instructional messages.
11 Advantageously, a PBX system according to the present 12 invention is capable of providing an individual copy of 13 each supervisory tone (in easily convertible digitally 14 encoded format) to each time slot requiring the tone, and therefore, is not subject to the tonal signal attenuation 16 that plagues conventional PBX systems. Furthermore, all 17 of the special features (e.g., voice mail, instructional 18 information, and music-on-hold), which according to the 19 prior art were provided only by using separate and distinct subsystems, may be provided, according to the 21 present invention, by the PBX system alone.
22 In a second aspect of the present invention, several 23 novel processes are provided for operating a PBX system in 24 order to provide special user services, like those described previously. For example, according to this 26 second aspect of the present invention, a novel method for 27 facilitating conference-type communication among three 28 desired time slots of a PBX system is provided. According 29 to one embodiment of this method intended for use in the preferred embodiment of a PBX system which includes a 31 feedback bus, the desired conference call time slots are 32 each connected to respective individual time slots of the 33 feedback bus. The three respective time slots are then 34 associated among themselves so as to form three unique pairs of time slots, in a manner that will be described 36 more fully hereinafter. Each of the constituent time W094/09603 2 ~ -4 6 6 ~ 2 PCT/US93/0960 ~

1 slots of each of the three pairs of time slots are then 2 converted from their pulse code modulated format to a 3 linear coded format, and next, the two time slots (now in 4 linear coded format) in each pair of time slots are added together to form three respective linear sums respectively 6 corresponding to each of the unique pairs of time slots.
7 The three respective linear sums are then reconverted to 8 pulse code modulated format and are supplied to additional 9 respective time slots of the feedback bus. Finally, in this method, the additional respective time slots are 11 connected by the switching means to the conference 12 callers' extensions such that each caller's input time 13 slot receives the sum of the other two callers' output 14 time slots. Thus, each caller is capable of hearing, talking to and exchanging data with the other callers in 16 the conference simultaneously. Advantageously, this 17 method (like each of the other methods according to this 18 aspect of the present invention, all of which will be 19 described shortly) requires no control hardware other than that which is already present in the PBX system.
21 In a third aspect of the present invention, a method 22 for implementing an improved "call forwarding" feature is 23 provided. In this method the presence of a call being 24 made to the PBX system is detected. The PBX system connects the incoming call to a caller-desired first 26 extension. After a predetermined period of time has 27 elapsed from the time that the incoming call was connected 28 to the first desired extension without that call being 29 answered at the first extension, the PBX system disconnects the incoming call from the first desired 31 extension and successively re-connects it, after 32 predetermined time periods have elapsed at each subsequent 33 extension or remote location without the call being 34 answered, to as many other successive subsequent predetermined extensions or remote locations as is 36 desired. In one embodiment of this third aspect, if the ~ 094/09603 2 1 ~ 6 6 ~ 2 PCT/US93/09609 1 extension or remote location sought to be connected to by 2 the incoming call is busy or otherwise occupied, the call 3 is connected automatically to the PBX system's voice mail 4 system. Also in this embodiment, the extension or remote location receiving the call may be prompted to provide a 6 password and/or predetermined string of digits and/or 7 characters in order to provide greater data security.
8 Advantageously, this embodiment of a novel call forwarding 9 method according to the third aspect of the present invention frees the intended recipient of the call from 11 having to answer the call in order to be able to receive 12 its information, and further, permits forwarding of the 13 call not only to a second extension within the PBX system 14 but also to a location remote therefrom. Thus, an intended recipient of a call need not be present in the 16 workplace to communicate using the PBX system, but rather 17 may communicate using the PBX from any location accessible 18 by ordinary public telecommunications networks.
1~ In a fourth aspect of the present invention, various voice message processing methods are provided. In one 21 method, according to this aspect of the present invention, 22 for automatically helping a user at an extension of the 23 PBX to use the system, verbal message storage means are 24 provided in which a plurality of digitized verbal messages related to helping the user use functions performable by 26 the system are stored. When initial user input is 27 detected by the system, the system prompts the user (by 28 transmitting an appropriate verbal message from the 29 plurality of digitized messages stored in the storage means to the extension), to select a desired function to 31 be assisted in using from a set of functions performable 32 by the system. The message transmitted by the system to 33 the extension informs the user as to the functions 34 performable by the system and various subsequent input(s) required to be supplied by the user to command the system 36 to instruct the user about those functions. The user's W094/09603 PCT/US93/0960 ~
214~2 -lo-1 subsequent input(s) is detected by the system and at least 2 one instructional message concerning the desired 3 function(s) is transmitted to the extension. Other voice 4 processing methods are also provided, according to this aspect of the present invention, and will be discussed in 6 greater detail hereinafter.
7 Other features and advantages of the present invention 8 will become apparent as the following Detailed Description 9 proceeds and upon reference to the Drawings, wherein like numerals depict like parts and in which:
11 Brief Description Of The Drawings 12 Fig. 1 is a functional block diagram of one embodiment 13 of a PBX system made according to the first aspect of the 14 present invention;
Fig. 2 is a system-level architectural block diagram 16 of the embodiment of a PBX system shown in Fig. l;
17 Fig. 3 is a functional block diagram of another 18 embodiment of a PBX system made according to the first 19 aspect of the present invention;
Fig. 4 is a system-level architectural block diagram 21 of the embodiment of a PBX system shown in Fig. 3;
22 Fig. 5 is a flow chart illustrating the steps of a 23 preferred embodiment of a method for generating 24 supervisory signals (according to the second aspect of the present invention);
26 Fig. 6 is a more detailed schematic block diagram 27 depicting component circuits of the embodiment of a PBX
28 system shown in Fig. 2;
29 Fig. 7 is a schematic block diagram of a preferred embodiment of an interface for connecting the control 31 means to the switch means in a PBX system made according 32 to the present invention; and 33 Fig. 8 is a more detailed schematic block diagram 34 depicting component circuits of the embodiment of a PBX
system shown in Fig. 4.
36 While the present invention will hereinafter be 21 ~ 6~52 ~ 0 94/09603 PC~r/US93/09609 --11-- ,. . -1 described in connection with preferred embodiments and 2 methods of use thereof, it will be understood that it is 3 not intended to limit the invention to these embodiments.
4 On the contrary, it is intended to cover all alternatives, modifications, and equivalents as may be included within 6 the spirit and broad scope of the various aspects of the 7 present invention as defined only by the appended claims.
8 Detailed Description Of Preferred Embodiments 9 Figure 1 shows the basic functional elements, in block diagram form, of one embodiment of a PBX system according 11 to the instant invention. Functionally, PBX system 10 12 comprises switching means 14 which has the ability to 13 interconnect any of the digitally encoded time division 14 multiplexed signal time slots of its input la, 2a, 3a, 4a and output lb, 2b, 3b, 4b, ports, respectively. Each of 16 these ports la, 2a, 3a, 4a, and lb, 2b, 3b, 4b, comprises 17 conventional bi-directional multiplexed buses. That is, a 18 time slot from an input port and corresponding output port 19 (e.g. la and lb) are used to provide a peripheral device extension for each device connected to the PBX system. As 21 is well known to those skilled in the art, extension 22 peripheral devices (not shown) may be connected to the 23 switching means 14 via the ports to permit at least one 24 time slot of the input ports to carry input data to the PBX system 10 and to permit data transfer from the system 26 10 (through at least one time slot of the output ports) to 27 the extension peripheral device. Thus, if appropriately 28 modified in obvious ways to those skilled in the art, a 29 PBX system according to the present invention is able both to upload from and download data to an external peripheral 31 device (not shown), such as a computer device. Also of 32 course, as will be appreciated by those skilled in the 33 art, the number of input and output ports illustrated in 34 any of Figures 1-4, 6, and 8 should not be viewed as narrowing the instant invention to using only a particular 36 number thereof, but rather, if appropriately modified in W 094/09603 PC~r/US93/09609 ~
2~ 4~2 -12-1 accordance with obvious techniques well known in the art, 2 a PBX system according to the present invention may 3 utilize any number of input and output ports. Also, each 4 of the input and output ports usually services between 24 and 32 time slots; however, as in the case of the number 6 of input and output ports, the number of time slots 7 serviced by each input and output port may vary without 8 departing from either the spirit or scope of the present 9 invention.
As depicted in Fig. 6, system 10 comprises a time 11 division combining means (shown by dashed lines) 27. This 12 combining means 27 itself comprises time division 13 multiplexer means, including multiplexer means 16 and 14 demultiplexer means 18, separate input means 26, separate output means 2 8 and feedback bus means 20. According to 16 this embodiment 10 of the first aspect of the instant 17 invention, the demultiplexer means 18 is connected to the 18 switch means 14 by feedback transmitting port 4b, while 19 also being connected to multiplexer means 16 via feedback 20 bus means 20. Multiplexer means 16 is connected l:o 21 feedback receiving port 4a which is in turn connected to 22 switching means 14.
23 Control means 12 is provided having connections 22 and 24 24 which permit, respectively, control and communication 25 with the storage means 30 and (via the switch 14) time 26 division combining means 27. The control means 12 is a~le 27 to control the operation of the PBX system 10 by, for 28 example, transmitting control data and/or signals to the 29 aforesaid elements of the system 10. Specifically, the transmission of the control data and signals make it 31 possible for the control means 12, inter alia, to direct 32 and control the switching means 14 in its assignment and 33 interconnection of data into time slots. Furthermore, as 34 will be described more fully hereafter, in this embodiment 10, the control means 12, by effectively controlling the 36 time division combining means 27, the storage means 30, 94/09603 2 1 ~ 6 6 ~ 2 PC~r/US93/09609 -13- ;

1 and the switching means 14, is able to provide desired 2 special user features including, for example, conference 3 calling capabilities, call forwarding, voice mail and 4 music-on-hold features, and other features, including on-line system messaging.
6 System 10 of this embodiment preferrably is connected 7 to an outside public telecommunications network (not 8 shown) by way of line interface circuits 38a and 38b, 9 (collectively referred to by numeral 38 in Fig. 6). These line interface circuits 38a and 38b are connected both to 11 the switching means 14 and to the input ports, 12 respectively. Analog communication signals entering the 13 system 10 from the outside network via lines 101, 102, are 14 converted, preferrably, into a bit stream having a conventional digital communications protocol, such as, 16 pulse code modulation (PCM) format and also are time 17 division multiplexed into time slots. In this way, analog 18 signals entering the system 10 via lines 101, 102 are 19 converted into a desired digitally encoded format and signals emitted by the system 10 of this embodiment, prior 21 to reaching the input ports la, 2a are reconverted from 22 this digitally encoded format to analog signal form to 23 permit transmission through the public network. of 24 course, the line interface circuits 38a, 38b may permit conversion to and from any number of desired encoding 26 formats, and, if either the system 10 or the public 27 network are appropriately modified, may be eliminated 28 entirely.
29 Likewise, extension interface means 40a, 40b, 40c, 40d, (collectively referred to as 40 in Fig. 6), in this 31 preferred embodiment, permit conversion of analog signals 32 to and from the encoded format to other desired formats.
33 As in the case of the line interface means 38a, 38b the 34 extension interface means 40a, 40b, 40c, 40d may permit signal conversion to and from an infinite variety of 36 encoding formats, or may be eliminated entirely.

W 094/09603 . PC~r/US93/09609 _ Coordination and generation of the TDM time slots is 2 preferably accomplished by timing means 70, which, 3 preferably comprises an Intel 5C 090-60 chip.
4 The control means 12 (preferably comprising a conventional microprocessor 50, such as, e.g., Intel 80X86 6 local bus interface 54, and ROM 60), in addition to being 7 capable of directing and interconnecting (by controlling 8 the switching means 14, which preferably comprises a 9 conventional MITEL MT8981DE chip) any of time slots of the input and output ports, is capable of generating and 11 distributing appropriate supervisory tonal signals to the 12 various ports. Two elements of the system 10 of this 13 preferred embodiment are important to the capabilities of 14 the control means 12. First, the system 10 is provided with feedback bus means 20. The control means 12, 16 according to the instant invention, is capable of 17 generating various supervisory tonal data signals 18 corresponding to standard and non-standard call-status 19 tones. The control means 12 transmits the supervisory data to the switch 14 via the control bus 24, the 21 preferred construction of which will be discussed more 22 fully, hereinafter. The switching means 14 then places 23 the data in respective time slots of the feedback bus 20 24 and transmits the data through the feedback transmitting port 4b. The control means 12 determines which of the 26 time slots of the feedback bus 20 is being respectively 2 7 occupied by the data. The supervisory signals may then be 28 recursively fed through the feedback bus 20 to feedback 29 receiving port 4a. Thereafter, advantageously, the control means 12 may distribute supervisory data in the 31 system 10 by controlling the switching means 14 so as to 32 connect the time slots of the ports lb, 2b, 3b to the data 33 in the time slots of the bus 20, to permit transmission of 34 data carried by the time slots of bus 20 to the port lb, 2b, 3b. Thus, preferrably, the supervisory data, prior to 36 being connected to the time slots of the ports lb, 2b, 3b, 94/09603 2 1 ~ 6 6 ~ z PC~r/US93/09609 1 travel through the feedback bus 20 at least once. Of 2 course, as has been described previously, the supervisory 3 data, prior to reaching the extensions to which it has 4 been connected undergoes conversion from its digitally encoded format to an appropriate analog format by the 6 extension interface means 40a, 40b, 40c, 40d.
7 A fuller explanation of the functioning of the time 8 division combining means 27 and the feedback bus means 20 9 in this preferred embodiment 10 will now be made.
Supervisory data (corresponding to respective supervisory 11 tones) generated by the control means 12 are transmitted 12 through the I/O bus 24 via bus interface means 54 to the 13 switch means 14 and are assigned to predetermined, unique, 14 respective time slots by the timing means 70 and the switch 14. Thence, the data (in respective time slots) 16 are fed through demultiplexer means 18, after being 17 transmitted through feedback port 4b, and travel through 18 bus 20. Thereafter, the data are inputted to feedback 19 port 4a, enabling the switch to connect the data to the other ports (and time slots thereof) lb, 2b, 3b, 4b) as 21 needed. Time slots of bus 20 are multiplexed in time by 22 means of the input multiplexer means 16. Since the 23 switching means 14 is capable of interconnecting any of 24 the time slots of the ports, any supervisory signal may be distributed to any desired extension by appropriate 26 control of the switching means 14 by the control means 12.
27 Turning now to Figs. 3, 4, and 8, a second preferred 28 embodiment of a PBX system according to the present 29 invention will now be discussed. In general, the elements and operation of preferred embodiment 10' are identical to 31 those of preferred embodiment 10, with the exception, that 32 feedback bus means 20 and time division combining means 27 33 (which are present in embodiment 10) are not found in the 34 second embodiment 10~.
Turning now to a discussion of the second aspect of 36 the present invention, complex call-status or supervisory W O 94/09603 '~ PC~r/US93/0960 ~
~ 6 ~ 2 -16-signals (with or without periodic cadence) may be 2 generated in the first embodiment 10, simply and 3 effectively, by using the switching means 14 and the novel 4 feedback bus means 20. According to this embodiment (for use in connection with the first embodiment 10) of the 6 second aspect of the instant invention, feedback bus 20 7 time slots carrying supervisory data and bus 20 slots 8 carrying silence data are alternatively cross connected to 9 time slots for carrying the complex data. Complex supervisory signals thus generated are transmitted by the 11 feedback bus 20 in their own, additional respective 12 individual time slots. If desired, by predeterminately 13 selecting the amount of time that silence data and 14 supervisory data are connected to the complex supervisory data time slot, the complex data may be made to have 16 periodic cadence. This complex data, either with or 17 without periodic cadence, may then be connected to any 18 time slot of the ports of the system by the switch 14, in 19 the manner that has been described previously.
More specifically, in order to generate complex 21 supervisory data according to this embodiment, the control 22 means 12 (by controlling the switching means 14) may cause 23 supervisory data entering the switching means 14 at 24 feedback receiving port 4a to be connected at the feedback transmitting port 4b to a desired time slot of the bus 20 26 dedicated to carrying complex supervisory data. The 27 control means 12 may next cause the switching means 14 to 28 connect a time slot carrying silence data (entering at the 29 receiving port 4a) to be cross-connected at the transmitting port 4b to the desired complex data time slot 31 of the bus 20. If periodic cadence for the complex data 32 is desired, the control means 12 may cause this connection 33 of the silence data time slot to the complex data time 34 slot of the bus 20 to be for a predetermined time and to re-occur at predetermined time intervals, however, it will 36 be appreciated that complex signals without periodic ~ O 94/09603 21 ~ 6 6S2 PC~r/US93/09609 1 cadence (that is, having arbitrary cadence or consisting 2 of combinations of supervisory signals without a silence 3 signal) may be generated according to this aspect of the 4 present invention without departing therefrom. The complex supervisory signals thus formed may then be 6 distributed to any extension in the system 10, in the 7 manner previously described.
8 Advantageously, by using this embodiment of a call-9 status signal distribution method, no signal attenuation results, unlike in the prior art. This is due to the fact 11 that, among other things, in the instant invention, each 12 time slot may be made to receive an individual copy of 13 desired supervisory data which may then be converted into 14 an individual analog wave form of the signal. Thus, as many extensions as are needed may be assigned by the 16 control means 12 and connected by the switch 14 to a bus 17 20 time slot containing a given supervisory or complex 18 signal without signal volume degradation.
19 Alternatively, in the second 10' embodiment, control means 12, generates various supervisory tonal signals 21 corresponding to standard and non-standard call-status 22 tones. The control means 12 transmits the supervisory 23 data to switch 14 via control bus 24. Switching means 14 24 then directly places the supervisory data in the time slots of the input and output ports to be connected to the 26 supervisory signals. Complex supervisory data in this 27 embodiment 10' are generated by control means 12 which 28 then supplies the complex data to the extensions of the 29 system 10' to receive the data via switching means 14.
More specifically, control means 12 generates supervisory 31 data corresponding to part (for example, a busy tone) of 32 the complex data and transmits that data to the switch.
33 The switch connects the supervisory data to the desired 34 extension (that is, the extension desired to receive the supervisory data). The control means then generates other 36 supervisory data, corresponding to the rest (for example, W O 94/09603 .~ PC~r/US93/0960 ~
~ 52 -18-1 silence data) of the complex data, which other data is 2 then connected to the extension to receive the complex 3 data. Since the control means 12, in this embodiment 10 4 is able to directly generate the complex supervisory data, no feedback bus 20 is needed to perform this function, as 6 in the first embodiment 10. In order to generate complex 7 supervisory signals having cadence, the control means 8 transmits the supervisory data making up the complex data 9 at predetermined time periods corresponding to the cadence desired for the complex data.
11 Continuing the discussion of the second aspect of the 12 instant invention, preferred methods for generating 13 supervisory data by the control means 12 will presently be 14 described. In connection with this discussion, reference should be had to Figs. 6 and 8. In both preferred 16 embodiments of the system 10, 10', the control means 12 17 comprises a microprocessor 50 having access to, and 18 control of, a circular memory buffer (not shown) comprised 19 within storage means 30. Storage means 30 preferably comprises, a circular memory buffer contained in RAM 62, 21 secondary storage means 64 (e.g., a hard disk drive) 22 interfaced to the bus 24 by standard disk controller means 23 56 (which may be a SCSI, RLL, IDE, or other type of 24 standard drive controller/interface means), and/or indicator means 200 (which preferably comprises Intel 26 5C090 chip for generating processor interrupts and/or 27 Direct Memory Accessing Signals for facilitating, among 28 other things, transfer of data in the system. The 29 microprocessor 50 generates a series of data values and stores these values in the circular buffer located in 31 storage means 30 after transmitting them through the 32 memory bus 22. The storage means 30 may either contain a 33 plurality of circular buffers in RA~1 62, each for 3~ containing respective call-status supervisory da~a corresponding to respective tones, or a single memory 36 buffer appropriately segmented into individual storage ~ 0 94/09603 21~66S2 PC~r/US93/09609 1 segments for storing said supervisory data therein in 2 accordance with well known conventional memory management 3 techniques. The microprocessor 50 is programmed so as to 4 implement a simple and efficient tone generating process, the steps of which are depicted in Fig. 5. As shown in 6 Fig. 5, numerical values represented by FI are converted 7 into an encoded form thereof, and are then stored 8 respectively in memory locations of the circular buffer 9 T ~ I ], where parameter I represents a given iteration step for generating supervisory signals. The numerical value 11 FI is assigned a value equal to (Gl* sin(I*2pi*C*N2) + G2*
12 sin(I*2pi*C*N3))/G3, wherein each of the variables Gl, C, 13 N2, G2, N3, and G3 correspond to values needed to generate 14 each type of status tone, and will thus vary depending on the signal to be generated. Also, the variables I and N
16 are iteration values and depend upon the size of the 17 buffer T[I] and location within the buffer TtI] of the 18 value FI being generated. Using readily available 19 publications of standard AT&T information, it has been determined that, in order to generate a standard U.S. dial 21 tone, N2 must be set equal to 350; N3 must be set equal to 22 440; Gl must be set equal to l; G2 must be set equal to 2;
23 and G3 must be set equal to 3. Data values FI for 24 generating a standard U.S. busy tone in this embodiment of the system 10 are also produced according to the above 26 equation, with the exception that the variables Nl, N2, 27 N3, Gl, G2, and G3, are set to 400, 480, 620, 1, 2, and 3 28 respectively. Lastly, to generate the audible ringing 29 tone, data values FI are produced that satisfy the above equation, except that the variable Nl, N2, N3, Gl, G2, and 31 G3 are set to 200, 440, 480, 1, 2, and 3, respectively.
32 Of course, as will be appreciated the above equation, by 33 selecting and substituting appropriate values for each of 34 the above variables, may be used to produce data for generating any type of arbitrary supervisory signal. The 36 FI values thus generated for each of the supervisory W 094/09603 21~ 2 -20- PC~r/US93/096 ~

1 signals are stored appropriately in the circular buffer 2 T[I] after having been converted to PCM format, using 3 commonly-known and readily available algorithms. Also, it 4 will be appreciated that, if desired, the data values FI
may be generated by the control means 12 in real-time and 6 need not be stored in the storage means 30.
7 Alternatively, the values FI may be pre-generated and 8 permanently stored in a ROM device or generated at system 9 10, 10' boot-up and stored in storage means 30, without departing from the instant invention.
11 In the first embodiment 10 of a PBX system according 12 to the present invention, the supervisory data 13 corresponding to respective supervisory tones are supplied 14 to the feedback bus 20 via the control means 12 through the control bus 24. The microprocessor 12 may be provided 16 with an appropriate interrupt service routine triggered 17 by, for example, indicator means 200, at periodic time 18 intervals (e.g., 125 microseconds) and values from the 19 buffer may be read from the storage means 30 and placed onto the I/O bus 22, and from there, placed onto the 21 control bus 24 by the control means 12. Thence, the 22 control bus 24 supplies these data to the switch 14 to 23 place them onto the feedback bus 20. Once the various 24 data values for the supervisory signals have been placed in respective time slots of the feedback bus 20, the 2 6 control means 12 may be used to connect these data values 27 to the ports. Also, by periodically cross-connecting the 28 various bus 20 time slots with each other and/or a bus 20 29 time slot dedicated to silence, in the manner described above), various complex supervisory signals having 31 periodic cadence may be generated.
32 Alternatively, in the second 10' preferred embodiment 33 of a PBX according to present invention, the supervisory 34 data are also supplied to the switch 14 via the control means 12 through control bus 24. The switch 14 then 36 connects the supervisory data to desired time slots (as ~ 094/09603 2 1 ~ 6 ~ ~2 PCT/US93/09609 1 determined by the control means 12) of the ports. Complex 2 supervisory data may be generated in the manner described 3 previously.
4 In another method according to the second aspect of the present invention, "music on hold" may be implemented.
6 In the first embodiment 10 of a PBX according to the 7 present invention, an interface circuit 36 connects an 8 external audio source 35 (which preferrably comprises a 9 conventional analog music source) to an encoding device 32 (all of conventional construction). The encoding device 11 32 converts analog audio or music signals supplied by the 12 audio source 35 into a digitally encoded format thereof.
13 Preferably, as has been described previously, this 14 digitally encoded form takes a form of a PCM-type encoding. Alternatively, of course, digitally encoded 16 audio signals may be stored in storage means 30 or some 17 other digital storage device (either in PCM format or some 18 other format and converted as needed). The encoded audio 19 data is then time division multiplexed and transmitted to the switch 14. In the first embodiment 10 of a PBX
21 according to the present invention, the data are then 22 connected to at least one dedicated time slot reserved 23 solely for such data of the feedback bus 20.
24 Alternatively, in the second embodiment 10', the data are directly connected by the switch 14 to at least one time 26 slot of the ports desired to receive music.
27 Advantageously, unlike the prior art, the incorporation of 28 the music on hold feature of the instant invention 29 reguires no additional control hardware other than that already present in the systems 10 and 10'.
31 Also, no additional hardware must be added to systems 32 10 and 10' to implement the voice mail feature according 33 to the second aspect of the instant invention. In the 34 first embodiment 10 of a PBX according to the present invention, incoming voice mail messages to be recorded may 36 be transmitted by the switching means 14 from any of the W O 94/09603 PC~r/US93/09609 2~ ~6~2 1 time slots of the input ports to a dedicated time slot 2 (voice record channel) of the feedback bus 20. Thence, 3 the data are inputted to port 4a. From there, the voice 4 data may be transmitted through the system bus 24 to the control means 12. Thence, the data may be transmitted to 6 either an external data storage device (not shown) via the 7 voice mail bus or may be stored in storage means 30 after 8 being transmitted through I/O bus 22. Of course, inasmuch 9 as the storage means 30 may comprise both secondary 64 as well as primary storage devices 62 the information 11 transmitted through I/O bus 22 may first be stored in 12 primary storage means 62 (e.g., random access memory) 13 until a sufficiently large bloc]~ of voice data is stored 14 therein and, thereafter,` may be dumped into secondary storage means 64 for future reading by the control means 16 12. Outgoing voice mail may be read either from the 17 separate storage device (not shown) or from the storage 18 means 30 by the control means 12. The data is then 19 transferred to the switch 14 so as to be placed into a second dedicated voice time slot (voice replay channel) of 21 the feedback bus 20, and from there the stored voice mail 22 data may be transmitted by the switching means 14 to any 23 extension requesting the replay of the voice mail message.
24 Alternatively, in the preferred embodiment of the voice mail system for use in the second embodiment 10', 26 voice mail messages to be recorded are transmitted by the 27 switching means 14 from the time slots of the input ports 2~ to the control means 12. Thence, data are inputted either 29 to an external data storage device (not shown) via the voice mail bus, or may be stored in storage means 30 after 31 being transmitted through I/O bus 22. Just as in the 32 first ~referred embodiment 10, inasmuch as the storage 33 means 30 may include both secondary 64 as well as primary 34 storage devices 62 the information transmitted through I/O
bus 22 may first be stored in primary storage means 62.
36 Outgoing voice mail may either be read from the separate ~ 0 94/09603 2 1 4 6 ~ ~ 2 PC~r/US93/09609 1 storage device (not shown) or from the storage means 30 by 2 control means 12. Data are then transferred to the switch 3 14 and transmitted to the extension requesting replay of 4 the voice mail message.
Thus, advantageously, a PBX system 10, 10' according 6 to the instant invention does not require special 7 combinations of dedicated timing instructions to 8 synchronize its voice mail and music on hold features with 9 the operation of the main system since all of these functions are controlled by the control means. Moreover, 11 no additional, special control hardware or transmission 12 lines are required to implement a voice mail feature 13 according to the present invention. Finally, inasmuch as 14 the voice mail feature is controlled using the existing control means for the system, and requires no separate 16 provisioning, the entire system may be administered 17 collectively, solely by the programming of control means 18 50, significantly decreasing system maintenance costs, 19 required administrative down-time, and complexity.
Also, according to the present invention, a method is 21 provided for facilitating conference-type communication 22 among three desired time slots of ports of a PBX system.
23 According to one embodiment this method for use in the 24 first 10 embodiment, the desired output time slots of the desired extensions are each connected to respective 26 individual time slots of the feedback bus 20 by the 27 switching means 14. The three respective time slots are 28 then associated among themselves as three unique pairs of 29 time slots consisting of two time slots each. For example, if the three time slots to be associated are 31 designated a, b, and c, respectively, the three unique 32 pairs resulting from their association would be given 33 respectively by: a and b; b and c; and, a and c. Each of 34 the time slots a, b, c are then converted from their coded format (as stated previously, preferably, pulse code 36 modulated format) to a linear coded format by the control W O 94/09603 PC~r/US93/09609.~
21~6~2 -24- ~

means 12. For example, the conversion from the coded 2 format to the linear format of each of the time slots 3 (that is the signals of each of the time slots) may 4 comprise the removal of format masking (for example, in 5 the case of a PCM code, logically XORing the data of the 6 channels a,b,c, with the value 55 hex and the removal of 7 Mu or A-law encoding). Conventional methods for 8 conversion of PCM coded data to linearly encoded data are 9 well known in the art, and any conventional PCM to linear 10 coding conversion method may be used in the method 11 presently being described, without departing from the 12 spirit or scope of the instant invention.
13 After converting each time slot a, b, c, each 14 associated pair (a and b; and c; and, a and c) of 15 linearly converted time slots are added together, to form 16 three respective linear sums of the three unique pairs of 17 time slots previously associated. These three respective 18 linear sums are then converted into pulse code modulated 19 format and are supplied to additional respective time 20 slots of the feedback bus 20. Of course, as in the case 21 of the conversion of the time slots into linear coded 22 format, the present conversion from the linear coded 23 format into pulse coded format may comprise well known 24 algorithms for doing same, without departing from the 25 instant invention. The three converted sums are then 26 supplied to additional respective time slots of the 27 feedback bus 20. The control means 12, by appropriate 28 manipulation of the switching means 14, may then connect 29 each of the conference caller's input time slots to each 30 of the sum signals, respectively, so that each of the 31 callers' input time slots receives the sum of the other 32 two callers' output time slots. Advantageously, this 33 permits each caller to hear, communicate with, and/or 34 exchange data with each of the other callers in the 35 conference.

36 Alternatively, in an embodiment of the method for use ~ 094/09603 21 ~ 6 6~2 PCT/US93/09609 1 in the second embodiment 10', control means 12 samples the 2 three unique pairs of time slots at predetermined time 3 periods. The sampling may be triggered by indicator means 4 200, which generates interrupt signals at predetermined time intervals. Data sampled from the time slots of the 6 three unique pairs are then converted from their coded 7 format to a linear coded format by the control means 12.
8 After converting the time slots sampled, they are added 9 together to form respective linear sums which are then reconverted to pulse code modulated format and are then 11 supplied via the switch to the third non-associated time 12 slot (that is, the time slot that was not part of the 13 unique pair sampled). The foregoing process is then 14 repeated for each of the other two unique pairs of time slots. Thus, each caller is permitted to hear, 16 communicate with, and/or exchange data with each of the 17 other callers of the conference.
18 As will be readily appreciated, no special control 19 hardware is required to implement this three-way conference calling feature according to the second aspect 21 of the present invention. This results in substantial 22 cost savings in the implementation of this feature.
23 Furthermore, as will be readily appreciated, the method of 24 this aspect of the present invention may be extended to any number of conference callers, in simple and obvious 26 ways to those skilled in the art, so that any number of 27 parties may be permitted to communicate simultaneously.
28 Preferably and advantageously, both embodiments of 29 this conference-calling method also comprise the generation and utilization by the control means of a look-31 up table matrix array stored in the storage means 32 containing all possible PCM data values for caller output 33 channels and their value after linearization, summing, and 34 reconversion to PCM. The control means may then index into the two dimensional look-up table array using, as 36 indexes, the respective data values in PCM code of each of W094/09603 PCT/US93/09609~
21~6 6~2 -26-1 the two associated caller output time slots to find their 2 PCM sum value after linearization which then may be sent 3 to the input time slot of the third non-associated 4 extension or remote location.
Advantageously, this arrangement permits the sum of 6 the two channels to be sent to the third extension's (or 7 remote location's) non-associated input channel without 8 the need to convert the two channels to and from the 9 linear coded format. Of course, the conference calling method previously described need not use such a look-up 11 table, but may rather incorporate the use of conventional 12 digital signal processing techniques to permit the 13 microprocessor 50 to decode, sum, and re-encode the time 14 slots of the extensions in real time, to permit conference calling according to the instant method. The choice of 16 whether the look-up table or the digital signal processing 17 approach to facilitate conference calling is used will be 18 dependent upon the capacity and speed of the storage means 19 30 and/or processing power of the control means 12.
Turning to the third aspect of the present invention, 21 a method for implementing an improved call forwarding 22 feature which may be used in both embodiments 10, 10' of a 23 PBX system according to the instant invention is provided.
24 One embodiment of the method according to this third aspect will be discussed in connection with Figs. 3 and 4.
26 In this embodiment of the forwarding method of the present 27 invention, the presence of a call being made to the PBX
28 system is detected, preferably, using conventional ringing 29 voltage detector means included in interface means 38a, 38b. A signal is then supplied ~y the detector means to 31 the control means 12. In response to the signal supplied 32 by the detector means, the voice mail system and method 33 previously described may be actuated in one embodiment of 34 this method, and the incoming caller is prompted by a recorded message retrieved from the storage means 30 (or 36 from alternative storage means, not shown) to supply a ~094/09603 2~ 2 PCr/US93/09609 desired extension. Any conventional method may be used to 2 accept the extension supplied by the caller (e.g., a dual-3 tone multi-frequency-type method and/or hook-flash 4 signalling methods). The control means 12 then uses the - 5 extension number supplied to cause the switching means 14 6 to connect the incoming call to the supplied extension 7 time slot. Of course, the caller may not be required to 8 supply an extension number, but rather, that number may be 9 stored in the storage means 30 and retrieved by the control means 12, or may be supplied using other means.
11 After a predetermined period of time has elapsed from the 12 initial time that the incoming call was connected by the 13 switching means 14 to the first desired extension without 14 that call being answered, the system 10 (or more particularly, the control means 12) causes the switching 16 means 14 to disconnect ~he incoming call from the first 17 desired extension, and the incoming call is then connected 18 by the control means 12 (via the switching means 14) to a 19 diferent, second predetermined extension or outside telecommunications line of the public network (not shown).
21 This new extension (or outside line) may be predetermined 22 and associated with the first extension in memory 30 23 (using conventional memory association techniques), so 24 that when needed, the control means 12 is able to connect the incoming caller to that second extension based on the 26 first extension supplied. Advantageously~ the se-ond 27 predetermined extension need not be connected to the 28 physical ports of the system 10, 10', but may rather be 29 located remote therefrom (e.g., at a location accessible 30 through a public network). As will be appreciated, the 31 associative memory space used by the control means 12 to 32 facilitate forwarding of the incoming calls may contain 33 more than one such successive orwarding extension (and 34 also, may include any number thereof), depending upon the 35 capacity of storage means 30 and the particular 36 application to which the system is put. Advantageously, ~14~52 1 outside forwarding of the incoming call is accomplished by 2 associating in the associative memory of the storage means 3 30, with the desired extension, an outside number for use 4 with the public telecommunications network. Means for dialing up and connecting the public network to a port 6 (preferably included in the line interface means 38) 7 controlled by the control means 12, which (after reading 8 the outside number from storage means 30) transmits the 9 number to the dialing and connecting means. The switch means 14 then connects the caller to the outside line of 11 the public network. In a variant of the foregoing call 12 forwarding method according to this third aspect of the 13 present invention, after the answering of the second (or 14 later) extension or remote~ location, the control means 12 may actuate an authorization request prior to permitting 16 data or message exchange between the caller and the 17 extension, by using the voice mail message system of the 18 instant invention. The one answering the call at either 19 the extension or the remote location may then be prompted to supply a password and/or predetermined string of digits 21 within a predetermined amount of time. The control means 22 12 may then evaluate the numbers and/or password supplied 23 from the extension or remote location against the 24 predetermined values stored in the storage means 30 therefor. If a correct numerical string and/or password 26 has been entered, the incoming call and the extension or 27 remote location may be permitted to exchange data or 28 transmit messages, while, if not, the incoming call may be 2q directed to the voice mail system by the control means 12, and data supplied by the incoming call may be stored into 31 storage means 30 for later recall by either the intended 32 recipient or by another alternative recipient having the 33 correct password (e.g., a secretary). For example, if, 34 after a predetermined amount of time, either the extension or the remote location do not answer the incoming call, 36 the incoming call may be directed by the control means 12 _ W094/09603 PCT/US93/09609 ~ 52 -29-1 via the switching means 14 to the storage means 30 or 2 external storage (not shown), according to the voice mail 3 method, and data supplied by the incoming call may be 4 stored in storage means 30 for later recall according to the voice mail feature of the instant invention.
6 Other novel methods for using a PBX 10, 10' made 7 according to the present invention will now be presented.
8 One such method is for automatically assisting a user at a 9 given extension of the system in using and/or learning about functions performable by the system (for example, 11 voice mail, call forwarding, and/or system administration 12 functions such as, configuring the input and output ports 13 of the system and assignment of extensions thereof).
14 According to one preferred embodiment of this method, a plurality of pre-recorded verbal instructional messages is 16 stored in the storage means 30 and/or special external 17 verbal message storage means (not shown). As will be 18 appreciated, such digitized verbal instructional messages 19 are infinitely variable, however, examples of such messages are listed in Table 1. Upon detection of initial 21 user input (which may comprise, for example, the entering 22 of a predetermined key sequence on a telephone keypad, the 23 initiation of a hook-flash signal by the user, use of dual 24 tone multi-frequency signals or other forms of conventional signals), the system 10, 10', and more 26 specifically, the control means 12, transmits an 27 appropriate message taken from the plurality of messages 28 stored in the storage means to the user at the extension.
29 This appropriate message prompts the user to select a desired function to be assisted in using and/or to learn 31 more about, from a predetermined set of functions 32 performable by the system, and recites subsequent input(s) 33 (associated with each of the functions in the set) 34 required to be supplied by the user to the system to effectuate this assistance. For example, as shown in 36 Table 1, the subsequent input associated with the W094/09603 PCT/US93/0960 ~
21~652 -30-1 extension configuration function is *6. Once the user has 2 determined which function of the system he desires to 3 learn about and/or implement, he may enter the 4 appropriate, subsequent user input associated with that function, which subsequent input is then detected by the 6 system. As was the case with the initial user input, the 7 subsequent user input may take many forms, but preferably 8 comprises a series of numeric keypad inputs from a 9 standard telephone, one or more hook-flash signals, and/or use of dual-tone multi-frequency signalling methods, 11 depending upon programming of control means 12 and the 12 prompting message supplied to the user. Once the system 13 detects the subsequent user input, an instructional 14 message about the desired function is transmitted from the storage means to the user. This verbal instructional 16 message provides assistance and/or information to the user 17 concerning how to access and/or use the desired function 18 provided by the PBX system 10, 10'. Optionally, according 19 to this method, the system 10, 10', prior to providing instruction on how to utilize the function desired by the 21 user, may prompt the user to supply a predetermined 22 password. In this way, various important system 23 administrative functions may be protected from tampering.
24 Also, optionally, the above process steps may be repeated until the user enters a predetermined key sequence or 26 other type of signal indicating that the user no longer 27 wishes to be assisted and/or instructed in using the 28 various features and/or functions performable by the 29 system. Also alternatively, at the end of the instructional message (or indeed, anywhere within the 31 steps of the method outlined above) the user may be 32 prompted by the system with a message intended to 33 determine whether the user wishes the system to perform 34 the desired function.
Also according to this aspect of the present 36 invention, various call-status verbal messages may be 0 94/09603 ~ 1 ~ 6 G ~ 2 PC~r/US93/09609 1 supplied to the user of the PBX system 10, 10'. For 2 example, after a predetermined amount of time has elapsed 3 after placement of a call, the system may send the user 4 placing the call a message indicating the status of the call, depending upon whether the extension being called is 6 busy, not being answered, or being automatically forwarded 7 to another extension, and so forth.
8 Turning now to Fig. 7, a preferred construction of 9 control bus 24 will now be described. For the sake of simplicity, only elements essential to a discussion of 11 control bus 24 are shown in Figure 7. As has been stated 12 previously, control bus 24 permits transfer of both 13 control signals to the switch and transfer of various data 14 (e.g., supervisory, voice mail, informational data, etc.) between the switch and control means. In this embodiment, 16 As shown in Fig. 7, the preferred embodiment of control 17 bus 24 comprises bi-directional data bus 110, address bus 18 120, chip select line 130, data strobe line 140, 19 read/write line 150, switch ready indicator 160, and data available line 210 interfaced to control means 50 via 21 indicator means 200.
22 In operation, in order to transmit data from the 23 control means 50 to the switch 14, control means 50 24 asserts select line 130, places an appropriate address onto address bus 120, appropriately sets read/write line 26 150 and data strobe 140 to fix the data transmission 27 direction of the data bus 110. Control means 50 then 28 places the data to be sent to the switch 14 onto data bus 29 110. After transfer of the data to the switch 14 (that is, after switch 14 has received the data), switch 14 31 appropriately sets ready line 160 to terminate transfer of 32 data from control means 50. When data is available from 33 switch 14 for transfer to the control means 50, the switch 34 14 indicates this condition by setting the data available line 210. This causes indicator means 200 to generate a 36 non-maskable interrupt signal which is sent to control W O 94/09603 ~ 32- PC~r/US93/0960 ~

1 means 50. The control means 50 then activates the 2 appropriate interrupt handler routine for receiving data 3 from the switch 14. Control means 50 then indicates its 4 readiness to receive data from the switch 14 by placing an appropriate address onto the bus 120, activates switch 6 select line 130, and by appropriately setting the 7 read/write line 150 and data strobe 140 to indicate a 8 "read" operation. The switch 14 then places the data to 9 be sent to the control means 50 onto the data lines 110.
After transfer of the data to the control means 50, switch 11 14 terminates the operation by asserting ready line 160.
12 Various changes may be made in the above-described 13 invention without departing from the spirit and scope 14 thereof. For example, call book-keeping (SMDR) information of the system 10, 10' may be gathered by the 16 control means 12 and stored in the storage means 30. At 17 periodic time intervals (generated for example by 18 interrupt means 200), the SMDR information stored in the 19 storage means 30 may be dumped therefrom into the alternative storage means (not shown) via the SMDR bus.
21 Also, storage means 30 and alternative storage (not shown) 22 may be used to contain program code for controlling the 23 sequence ol operations to be performed by the 24 microprocessor 50 in the above-detailed preferred embodiment of the system 10 according to the instant 26 invention. Additionally, the system 10, 10' or the 27 present invention may automatically inform the user 28 thereof as to the number of voice mail messages received 29 for the user and may also provide the user with summaries of the contents of such messages automatically or upon 31 provision of a predetermined input from the user. The 32 system may prompt the caller leaving voice mail to leave a 33 summary of his message, in order to provide this summary 34 to the intended recipient of the message. Other variations are also possible without departing from the 36 present invention. For example, the fourth aspect o~ the ~ 094/09603 PCT/US93/09609 ~ 6s? -33-1 present invention may be modified so that at least one of 2 the functions performable by the system 10, 10' permits 3 the user to define and/or formulate a user-defined 4 function which may comprise one or more standard functions performed by the system in sequence. Accordingly, the 6 present invention is intended only to be limited by the 7 hereinafter appended claims.

W O 94/09603 PC~r/US93/0960 ~
~,~ 4~S~ ~

3 Option 1 message: "To call another extension, 4 enter the extension number or dial *1 to call that person by 6 last name."

8 Option 2 message: "To make an outside call, dial 9 g or dial the extension number assigned to the particular line 11 through which you wish to call."

13 Option 3 message: "To access your abbreviated 14 messages, dial *8."
16 Option 4 message: "To program abbreviated dialing 17 numbers, enter *3 and follow 18 instructions. To use your 19 abbreviated dialing numbers enter #n", where n is a number 21 from 0 to 9."

23 Option 5 message: "To configure the system dial 24 *4."
26 Option 6 message: "To configure your extension, 27 dial *6."

29 Option 7 message: "To configure an outside line, dial *7 followed by the 31 extension number for that line."

Claims

1. A private branch exchange system (10,10') having a plurality of input and output ports, each of said ports having a plurality of digitally encoded time division multiplexed signals in a plurality of time slots, said system (10,10') comprising:
a. control means (12) for controlling operation of said system (10,10') and also being programmed to generate supervisory data;
b. switch means (14) for interconnecting any of said plurality of time slots of said ports (1a,b, . . .
4a,b), said switch means (14) being connected to said control means (12) so as to be able to receive both control data and supervisory data therefrom, said switch means (14) also being for transmitting supervisory data received to at least one port (1a,b, . . . 4a,b) selected by said control means (12); and c. means (38) for connecting at least one selected time slot of said input ports to an outside public communications network having a plurality of remote locations accessible by said public communications network, said connecting means (38) being capable of accessing said remote locations through said public communications network.

2. A system (10,10') according to claim 1, wherein said control means (12) is capable of generating complex supervisory data.

3. A system (10,10') according to claim 2, wherein said control means (12) is capable of generating complex supervisory data having cadence.

4. A system (10,10') according to claim 3, wherein said cadence has a predetermined periodicity.

5. A system (10,10') according to claim 1, and further comprising, storage means (30) for containing message data, said control means (12) being able to transmit said message data to said storage means (30).

6. A system (10,10') according to claim 5, wherein said storage means (30) is adapted to receive digitized voice messages from said switch (14), store said message data, and re-transmit said message data to said switch (14).

7. A system (10,10') according to claim 5, wherein said storage means (30) contains message data for assisting in use of the system (10,10').

8. A system (10,10') according to claim 5, wherein:
i. said control means (12) comprises processor means (50) and system bus (24) means permitting communication between said system (10,10') and said processor means (50); and ii. said storage means (30) comprises a circular memory buffer array for storing said supervisory data.

9. A system (10,10') according to claim 1, wherein said system (10,10') is also capable of combining desired time slots of said input (1a . . . 4a) and output ports (1b, . . . 4b) to permit conference-type communication among said time slots of said ports (1a,b, . . . 4a,b).

10. A method for facilitating conference-type communication among three desired extensions' output time slots of a digital private branch exchange system (10) having a plurality input ports (1a, . . . 4a) corresponding to a plurality of incoming communications and a plurality of output ports (1b, . . . 4b) corresponding to a plurality of outgoing communications including at least one feedback receiving (4a) and transmitting port (4b), each of said plurality of input (1a, . . . 4a) and output (1b, . . . 4b) ports having a plurality of digitally encoded time division multiplexed signals, each in a pulse code modulated format, in a plurality of time slots, said system (10).comprising control means (12) for controlling operation of said system (10), switch means (14) for interconnecting any of said plurality of time slots of said ports (1a,b . . .

4a,b), feedback bus means (20) for connecting said at least one feedback receiving (4a) and transmitting (4b) ports, and means (38) for connecting at least one selected time slot of said input ports to an outside public communications network having a plurality of remote locations accessible by said public network, said connecting means being capable of accessing said remote locations through said public network, said method comprising the steps of:
a. connecting said three desired output time slots to respective time slots of said feedback bus (20);
b. associating said three desired output time slots to form three unique pairs of said desired time slots, each said pair consisting of two of said desired output time slots each;
c. converting each of said two output time slots of each of said three unique pairs of desired output time slots from said pulse code modulated format into a linear coded format;
d. summing each of said two output slots converted into said linear coded format of each of said three unique pairs of desired output time slots to form three respective linear sums corresponding respectively to each said unique pair;
e. reconverting each of said three respective linear sums from said linear coded format into pulse code modulated format;
f. supplying each said reconverted sums to additional respective time slots of said feedback bus (20); and g. respectively connecting each said additional time slot to a desired extension input time slot not included within the corresponding unique pair of each said additional time slot.

11. A method according to claim 10, wherein steps c-e respectively comprise the use of digital signal processing techniques, and wherein the converting of each said two slots from said pulse code modulated format into said linear coded format at step c includes the elimination of mu-law or A-law encoding.

12. A method according to claim 10, and further comprising:
h. generating data corresponding to fixed values useful in converting said desired slots to said linear format and in reconverting said linear sums into pulse code modulated format; and i. storing said data generated in step h in an associative memory array.

13. A method according to claim 12, wherein said fixed values comprise all possible reconverted sum data values for said two output time slots; and, said associative memory array is a two dimensional matrix array having indexes M and N corresponding to all possible pulse code modulated data values for each of said two output time slots and said fixed values are stored in said matrix so that a particular reconverted sum data value of actual pulse code modulated data values of said two output time slots may be accessed by using said actual values as indexes, respectively, into said matrix array.

14. A method for controlling a private branch exchange system (10,10') as claimed in claim 1, wherein said control means (12) generates supervisory data equal to FI wherein FI is calculated using the formula [G1* sin(I*2*pi*C*N2)+G2*sin(I*2*pi*C*N3)]/G3, wherein G1, I, C, N2, G2, N3, and G3 are variables.

15. A method according to claim 14, wherein the variables N2, N3, G1, G2, and G3, are set equal to, respectively, 350, 440, 1, 2, and 3.

16. A method according to claim 14, wherein N2, N3, G1, G2, and G3, are set equal to, respectively, 480, 620, 1, 2, and 3.

17. A method according to claim 14, wherein the variables N2, N3, G1, G2, and G3 are set equal to, 440, 480, 1, 2, and 3, respectively.

18. A call forwarding method for use in a system (10,10') according to claim 1, and comprising the steps of:
a. connecting an incoming call from one time slot of said input ports to a desired extension time slot;
and b. disconnecting said call from said desired time slot, after a period of time has elapsed, and reconnecting said call to said at least one remote location associated with said desired time slot, said remote location being accessed through said public communications network by said connecting means (38).

19. A call forwarding method according to claim 18, and further comprising, prior to allowing transfer of data from said incoming call to said remote location, requiring submission of a password from said remote location.

20. A call forwarding method according to claim 18, wherein said remote location is a second desired extension.

21. A call forwarding method according to claim 20, and further comprising, prior to allowing transfer of data from said incoming call to said remote location, requiring submission of a password from said remote location.

22. A method for facilitating conference-type communication among a plurality of desired extensions' output time slots of a private branch exchange system (10) having a plurality input ports (1a, . . . 4a) corresponding to N of incoming communications and N of output ports (1b, . . . 4b) corresponding to a plurality of outgoing communications including at least one feedback receiving (4a) and transmitting port (4b), each of said plurality of input (1a, . . . 4a) and output (1b, . . .
4b) ports having a plurality of digitally encoded time division multiplexed signals, each in a pulse code modulated format, in a plurality of time slots, said system (10) comprising control means (12) for controlling operation of said system (10), switch means (14) for interconnecting any of said plurality of time slots of said ports, feedback bus means (20) for connecting said at least one feedback receiving (4a) and transmitting (4b) ports, and means (38) for connecting at least one selected time slot of said input ports to an outside public communications network having a plurality of remote locations accessible by said public communications network, said connecting means being capable of accessing said remote locations through said public communications network, said method comprising the steps of:
a. connecting said plurality of desired output time slots to respective time slots of said feedback bus;
b. associating said plurality of desired output time slots to form N unique groups of said desired time slots, each said group consisting of N-1 of said desired output time slots each;
c. converting each of said N-1 output time slots of each of said unique groups of desired output time slots from said pulse code modulated format into a linear coded format;
d. summing each of said N-1 output slots converted into said linear coded format of each of said groups of desired output time slots to form a plurality of respective linear sums corresponding respectively to each said unique group;
e. reconverting each of said plurality of respective linear sums from said linear coded format into pulse code modulated format;
f. supplying each said reconverted sums to additional respective time slots of said feedback bus; and g. respectively connecting each said additional time slot to a desired extension input time slot not included within the corresponding unique group of each said additional time slot.

23. A method according to claim 22, wherein steps c-e respectively comprise the use of digital signal processing techniques, and wherein the converting of each said N-1 time slots from said pulse code modulated format into said linear coded format at step c includes the elimination of mu-law or A-law encoding.

24. A method according to claim 22, and further comprising:
h. generating data corresponding to fixed values useful in converting said desired slots to said linear format and in reconverting said linear sums into pulse code modulated format; and i. storing said data generated in step h in an associative memory array.

25. A method according to claim 24, wherein said fixed values comprise all possible reconverted sum data values for said N-1 output time slots; and, said associative memory array is a matrix array having indexes corresponding to all possible pulse code modulated data values for each of said N-1 output time slots and said fixed values are stored in said matrix so that a particular reconverted sum data value of actual pulse code modulated data values of said N-1 output time slots may be accessed by using said actual values as indexes, respectively, into said matrix array.

26. A method for automatically assisting a user of a private branch exchange system (10,10') in using said system (10,10'), said system (10,10') having a plurality of input (1a, . . . 4a) and output (1b, . . . 4b) ports, each of said ports (1a,b, . . . 4a,b) having a plurality of digitally encoded time division multiplex signals in a plurality of time slots, said system (10,10') including control means (12) for controlling operation of said system (10,10'), switch means (14) for interconnecting any of said plurality of time slots, storage means (30) for storing a plurality of verbal messages related to assisting said user in using said system (10,10'), and means (38) for connecting at least one selected time slot of said input ports to an outside public communications network having a plurality of remote locations accessible by said public network, said connecting means being capable of accessing said remote locations through said public network, said method comprising the steps of:
a. detecting an initial user input to said system (10,10');
b. prompting said user to select a desired function to be assisted in using from a set of functions performable by said system (10,10') by transmitting an appropriate message from said plurality of messages to said user, said appropriate message reciting said set of functions and subsequent inputs associated with each of said set of functions required to be inputted to be assisted in using said functions; and c. detecting subsequent user input associated with said desired function.

27. A method according to claim 26, and further comprising, transmitting to said user an instructional message concerning said desired function from said plurality of messages.

28. A method according to claim 26, wherein said initial user input comprises a predetermined string of keypad entries.

29. A method according to claim 26, wherein said initial user input comprises use of a hook-flash signal.

30. A method for automatically assisting a user at an extension of a digital private branch exchange system (10,10') according to claim 1 in using said system, said method comprising:
a. storing in storage means (30) a plurality of digitized verbal messages related to assisting said user in using functions performable by said system (10,10');
b. detecting an initial user input to said system (10,10');
c. prompting said user to select a desired function from a set of functions performable by said system (10,10') by transmitting an appropriate message from said plurality of messages to said extension, said appropriate message reciting said set of functions and subsequent inputs associated with each of said set of functions;
d. detecting subsequent user input associated with said desired function; and e. transmitting to said extension an instructional message about said desired function from said plurality of messages.

31. A method according to claim 30, and further comprising, repeating steps c-e until a termination signal is detected.

32. A method according to claim 30, and further comprising, after step e, the following additional step:
f. prompting said user to command said system (10,10') to perform said desired function.

33. A system (10,10') according to claim 1, wherein message data is stored in storage means (30), is related to voice mail, and is transmitted to at least one time slot upon occurrence of a predetermined event.

34. A system (10,10') according to claim 33, wherein said event comprises a hook flash.

35. A system (10,10') according to claim 1, and further comprising, indicator means for indicating to said control means that data is to be transmitted in said system.

36. A system according to claim 35, wherein said indicator means (200) is able to transmit an interrupt signal to said control means (50).

37. A system (10,10') according to claim 36, wherein said interrupt signal is non-maskable.

38. A system (10,10') according to claim 1, wherein said data is transferred in said system (10,10') by using direct memory access techniques.

39. A system (10,10') according to claim 1, wherein said supervisory data comprise verbal supervisory data corresponding to at least one verbal call-status message stored in storage means (30).

40. A system (10,10') according to claim 39, wherein said at least one verbal message includes an error message indicating that a call placed through the system cannot be completed to an intended recipient thereof.

41. A private branch exchange system (10,10') having a plurality of input (1a, . . . 4a) and output ports (1b, . . .4b), each of said ports (1a,b, . . . 4a,b) having a plurality of digitally encoded time division multiplexed signals in a plurality of time slots, said system (10,10') comprising:
a. control means (12) for controlling operation of said system (10,10') and also for generating supervisory data;
b. switch means (14) for interconnecting any of said plurality of time slots of said ports, said switch means (14) being connected to said control means (12) so at to be able to receive both control data and supervisory data therefrom, said switch means (14) also being for transmitting supervisory data received to at least one port selected by said control means (12);
c. storage means (30) for storing supervisory data generated by said control means (12) and for supplying said stored supervisory data to said switch means (14); and d. means (38) for connecting at least one selected time slot of said input ports to an outside public communications network having a plurality of remote locations accessible by said public communications network, said connecting means (38) being capable of accessing said remote locations through said public communications network.

42. A system (10,10') according to claim 41, wherein said storage means (30) is also for storing verbal message data corresponding to a plurality of verbal messages related to operation of said system (10,10').

43. A system (10,10') according to claim 42, wherein at least one of said plurality of verbal messages is a verbal instructional message for assisting said user to learn how to operate said system (10,10').

44. A method according to claim 32, and further comprising, after step f, the following step of:
g. performing said desired function commanded by said user.

45. A method according to claim 32, wherein said desired function permits said user to define at least one user-defined function.

46. A method according to claim 45, wherein said user-defined function comprises a sequence of standard functions.

47. A method according to claim 44, wherein said desired function is an abbreviated dialing function.

48. A method according to claim 44, wherein said desired function is a function for changing a system access password.

49. A call-forwarding method for use in a system (10,10') according to claim 1, and comprising the steps of:
a. connecting an incoming call from at least one time slot corresponding to a desired extension; and b. disconnecting said call from said desired extension and reconnecting said call to at least one other extension.

50. A call-forwarding method according to claim 49, and further comprising, between steps a and b, prompting for input of said at least one other extension.

51. A call forwarding method according to claim 49, wherein said at least one other extension comprises at least one remote location accessible using connection means (38) via an outside public communications network.

52. A call-forwarding method according to claim 49, and further comprising, prompting for entry of said at least one other extension between steps a and b, said prompting comprising use of verbal message data stored in said storage means (30), said message data corresponding to at least one verbal message.

53. A call-forwarding method according to claim 52, wherein said at least one verbal message comprises a message indicating that said desired extension is busy.