CA2043598C - Telemetry access arrangement - Google Patents
Telemetry access arrangementInfo
- Publication number
- CA2043598C CA2043598C CA002043598A CA2043598A CA2043598C CA 2043598 C CA2043598 C CA 2043598C CA 002043598 A CA002043598 A CA 002043598A CA 2043598 A CA2043598 A CA 2043598A CA 2043598 C CA2043598 C CA 2043598C
- Authority
- CA
- Canada
- Prior art keywords
- connection
- customer
- establishing
- over
- signals
- 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 - Lifetime
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M11/00—Telephonic communication systems specially adapted for combination with other electrical systems
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M11/00—Telephonic communication systems specially adapted for combination with other electrical systems
- H04M11/002—Telephonic communication systems specially adapted for combination with other electrical systems with telemetering systems
Abstract
This invention relates to a method and apparatus for accessing customer meters and for controlling customer devices over a telephone line. A suppressed ringing connection is established over a customer line between a central office and customer station equipment. The connection is between a data accessing device such as a meter reading controller and a customer premises device such as a meter interface unit. Signals are exchanged over the connection between these two units without alerting the customer via a ringing signal and without changing the supervisory state of the customer's station equipment from on-hook. The connection can also be used for controlling devices such as air conditioning units, in order, for example, to avoid overloads in a power distribution system. The voice switching network of the central office is used for making the connection between the meter control unit and the meter interface unit. Advantageously, this arrangement can allow a large number of utility meters and controlling devices to be accessed remotely using existing telephone plant.
Description
TELEMETRY ACCESS ARRANGEMENT
Technical Field This invention relates to a method and apparatus for accessing customer meters and for controlling customer devices over a telec~ mullications line.
5 Problem There has long been a need for reading utility meters periodically, a need which in the past has been met largely through manual arrangements. More recently, there has also been a growing desire by the electric power utilities to be able to control consumer electric loads as a means of forestalling brownout and 10 blackout situations. This need has been met with only partial success in the prior art by tel~,llc~e ing arrangements associated with telephone customer line access and by the use of carrier systems connected to power distribution lines. In these arrangements, utility meters at a telephone customer's home or business are accessed via the telephone customer's line when that line is not being used for telephone calls.
15 The method of accessing the line is to have a direct metallic path between the customer's meter reading interface and a service unit at the central of fice formonitoring and controlling the off-hook/on-hook supervisory state of the customer.
Access from the central office switch to the customer is provided through the use of a no-test trunk, i.e., a trunk which can access a customer's line even when that line is 20 already in the off-hook state. The trunk uses a no-test connection, i.e., a special metallic connection that bypasses the normal switched telephone connection and connects without making a busy test. This metallic connection passes direct current signal. The no-test trunk is used to get access to the meters without ringing the customer's line, the latter action being performed on all conventional telephone25 connections. The meter is then triggered to respond by being sent signals over the no-test connection, each signal consisting of a burst of tone of one of thirteenfrequencies in the telephone voice band. Using this arrangement, a connection isestablished to the customer's line, the service unit makes a test whether the customer is busy, and, if the customer is not busy, the service unit is connected to the 30 customer's meter interface. The meter interface is primed (alerted) by one of the thirteen frequencies to respond to data signals originating from the service unit or a controller at the utility, tr~nsmitted via the service unit. These data signals may be either in the form of dual tone multifrequency (DTMF) signals or frequency shiftkeyed binary data signals. Following the alerting of the meter interface unit, there is 35 an exchange of signaling information between the controller and the meter interface unit, the signaling exchange being used for triggering the reading of meters, for tr~n~mitting the present reading of the meters, for returning the present status of these meters, or for controlling a device such as an air conditioner at the called customer's residential or business location. The latter function allows a power S company to control its peak load by tempc,l~ily shutting down, possibly on a rotating basis, a portion of the air conditioners being served. The actual reading of the meters is performed by a reading mechanism that interfaces with the meter interface used. Meter status information includes indications of customer tampering, low battery, or other indic:ltions of a need for servicing. After a complete cycle of 10 meter readings and/or device control operations has been completed, the no-test connection is dropped and the customer is enabled to originate new calls.
While the customer's line is connected to the service unit, supervision of the customer's line is performed by the central office service unit (C.O. service unit) which is connected by a metallic access connection that provides current sensing15 supervision from a central office service unit. In modern digital switching systems, such as the SESS~) switch manufactured by AT&T, and described in The AT&T
Technical Journal, July/August 1985, no metallic access connection is provided through the voice network, so that a no-test trunk is required for monitoring direct current supervisory signals. If the customer's telephone station goes off-hook, a 20 direct current in excess of 20 milli~mperes is detected by the C.O. service unit and the central office service unit disconnects the telemetry call. In some cases, the supervision is p~lrolllled from the customer's meter interface unit which transmits a disconnect signal to the central office service unit to disconnect the telemetry call.
There are a number of disadvantages to this arrangement. The no-test 25 trunk is a facility available in very small numbers in a central office, the number being limited by the no-test access arrangements. No-test trunks are used primarily for checking on customers whose lines are reported as being busy for too long a time, making tests of the resistance between the two wires of a customer line, and manual testing of a line. In a typical switch, such as the SESS switch, only two no-30 test trunks are available in an entire switch, which may serve up to several hundredthousand customer lines. In a typical meter reading cycle the time required for meter readings and/or device control operations may vary from 10 to 20 seconds. Clearly, two no-test trunks are inadequate to serve the meter reading and device control needs of all the customers of the SESS switch. Further, the requirement for a direct 35 metallic path in order to provide current sensing supervision makes it difficult to access lines which are not connected directly to a switch but are connected through a 20~35g8 subscriber line carrier system, such as the SLC 96 (Subscriber Line Carrier) manufactured by AT&T, since such SLC systems do not provide a metallic path for a normal voice connection. Further, billing records for such no-test trunk calls are made separately from the billing records for voice or data calls, thus creating S a-lmini~trative problems. Further, in prior art arrangements, if a customer wishes to originate a call while the meter reading is taking place, there are some arrangements in which the customer is blocked until the reading is completed and other arrangements in which the customer is blocked for a period of 1 to 2 seconds until the no-test connection can be dropped.
Because of the small number of no-test trunks and limited no-test access, and the fact that the no-test trunks are needed for their primary intended purposes, the number of meters which may be monitored and devices which may be controlled is much smaller than the number of such meters and devices served by a typical large local central office. It is costly to add substantial numbers of extra no-15 test trunks, in a digital switch such as the SESS switch which does not provide a metallic access voice switching network, because the metallic access unit provided for such no-test trunks is expensive. A problem of the prior art, therefore, is that there is no arrangement available which permits a large central office, especially a digital central office which does not provide a direct metallic path for telephone 20 connections, to access a large number of meter reading and device control interfaces within a reasonable period over the customer lines connecting that central of fice to the telephone stations and the remote metering devices.
Solution The above problem is solved, in a departure from the prior art by 25 providing, for example, arrangements wherein a standard interoffice trunk, controllable by special soflw~ of the connected ~wilchi-lg system, is used for accessing, over an analog customer line, a customer's premises device such as a meter interface unit (MIU) from a data access device, such as a utility meter reader/device controller; this standard trunk is then connectable to the customer's 30 line via a suppressed ringing connection through the co~ nunication signal switching network, used, for example, for voice signals, in order to access the customer's analog line, connected to the MIU. Advantageously, such an arrangement makes it possible to use a plurality of circuits for accessing different meter interface units at the same time and without requiring additional expensive 35 specialized no-test trunks.
Modern digital switching systems, such as the SESS switch, do not provide a metallic connection that can pass direct current signals; metallic access facilities are expensive in digital switches because they bypass the digital network which is used for passing speech signals for telephone conversations. The switching S network need not provide a metallic access from the C.O. service unit to the line because supervision is detected at the line circuit, an interface between the switching network and the customer line, and is passed by the software controlled processors of the switch to the connected trunk, which passes supervision to the C.O. service unit.
Trunks such as the well-known E & M trunks or trunks using common channel 10 ~ign:~ling have arrangements for colllnlu-licating a change in supervisory state at one end to the other end of the trunk. These arrangements are used to transmit customer supervisory state changes to the C.O. service unit so that the unit may disconnect if a customer goes off-hook.
In the prior art, the only way of getting access to a customer's line using 15 the standard switching network or switch fabric was to ring the customer's line, and to monitor supervision from a line circuit in the switch. In a departure from the prior art, a new type of call connection is made in which ringing is suppressed in order to avoid alerting the customer; supervision is monitored by the switch and transmitted via the software controlled processors and trunk supervisory signal transport 20 techniques to a mo~ o~ g central office unit. The meter interface unit is alerted without ringing the customer's line from a connection through the standard switch fabric of the central of fice by providing a new class of service for calls from the utility, the new class of service being characterized by a connection made without such ringing. In this case, the class of service is a class of service of the caller and 25 affects the nature of the call being set up. The meter interface unit is alerted that a connection to the meter interface is desired by a tone sent to the interface unit by the C.O. service unit, or, altern~tively, by the utility controller through the service unit.
The interface unit receives these tones while in the on-hook state and processes them without sending an off-hook signal back to the central office.
Billing records are made in the normal way that billing records are made for calls through the switching network. Advantageously, this type of call connection can use the normal switch fabric for accessing a customer line, while also providing the absence of ringing necessary to access the meter interface unit without disturbing the customer, and while continuing to use normal customer supervision35 from the switch.
Present-day subscriber line carriers (SLCs) will not set up a connection unless they detect ringing. An exception to this rule is for a connection from a no-test trunk wherein a special tone is provided which is recognized by the subscriber line carrier and which will then provide a metallic bypass of the SLC. In accordance 5 with one aspect of the invention, when a meter interf~ce unit access call is set up through a subscriber line carrier, a brief burst of ringing is applied on that connection. In response to that brief burst of ringing, the subscriber line carrier sets up a connection within its own switch fabric to the called customer whose meter interface unit is being accessed. The burst of ringing is sufficiently short that the 10 subscriber line carrier which repeats any ringing signals that it detects on its input, will not in fact repeat any ringing signal to that customer's line, thus, avoiding disturbing the customer when only the meter interface unit is being accessed.
A central office service unit interfaces between a utility controller, such as a personal ColllpuLt;l, at the utility and the meter interface unit connected through 15 the voice signal switching network. Responsive to signals from the utility controller, the central office service unit signals the switch with the identification of the called customer to set up a suppressed ringing connection to the desired meter interface unit. The central office service unit or utility controller transmits alerting signals to the meter interface unit. The central office service unit detects off-hook signals from 20 the switch in order to signal for a premature disconnect, and responds to a meter interface unit disconnect signal to signal the switch for a disconnect of the meter reading and/or device control connection. The central office service unit has a plurality of interorrlce trunks for co,~ icating with customers connected to other switching systems and for collullunicating simlllt~neously for reading several meters 25 in parallel for customers in these switching systems; it also is connectable to a plurality of utilities for simultaneous use over different trunks.
In accordance with one aspect of the invention, for an Integrated Services Digital Network (ISDN) station connected via a Primary Rate Interface or a Basic Rate Interface, and a digital line, the D-channel is used for colllnlullicating 30 with the meters and controllable devices. This also permits the comlliullication signal switching network to be used for providing access to the customer's lines and allows the high bandwidth (64 or 16 kb./sec.) D-channel to be utilized for col~ lunications with the meters and devices. Here, supervision is detected at the customer premises and is tr~n~mitted by data signals over the D-channel.
-6- 20Q~3~j98 Accordingly, this invention provides a method and apparatus for accessing customer premises devices from a data access device by using a suppressed ringing connection through a voice signal switching network of a teleco~ unications switching system.
S In accordance with one aspect of the invention there is provided atelephone switching system comprising: a switching network for interconnecting amultiplicity of telecommunications trunks and another multiplicity of analog customer lines; at least one of said trunks connectable to a utility data accessing device for accessing a customer premises device; and processor means operative under the control of a program for translating a class of service of said at least one of said trunks, and responsive to said tr~nCl~ting~ for establishing a connection through said network without transmitting ringing signals to an analog customer line.
In accordance with another aspect of the invention there is provided a method of accessing a customer premises device from a data accessing device via a telecommunications switching system, said telecommunications switching system comprising a voice band signal switching network for switchably interconnecting multiplicities of inlets and multiplicities of outlets, said inlets for connection to interoffice telecollllllunications trunks, said outlets for connection to analogcustomer lines, the method comprising: determining that a class of service for an inlet connected to said data ~CCPscing device is a class of service requiring establishment of a suppressed ringing connection; establishing a suppressed ringing connection from said inlet to an outlet of said voice band signal switching network for connecting said data accessing device to an analog customer line connected to station equipment of a customer; and transmitting signals over said suppressed ringing connection for accPccing said customer premises device over said analog line from said data accessing device.
Brief Description of the Drawing FIG. 1 is a block diagram illustrating connections for accessing customer meters and devices; and FIGs. 2-6 are flowcharts of actions performed in setting up such connections and in accessing meters and devices.
P
- 6a - 20 ~35g8 Detailed Description FIG. 1 is a block diagram of the operation of applicant's invention.
A terminal such as a personal computer 10 at the office of a utility is connected by a line or connected over an interoffice trunk to a telephone switch 21. When an 5 access number is dialed and received from PC 10 in switch 21, a connection is set up to a central office service unit 20. The central service unit is located herein in a first central office that includes switching system (switch) 21. In alternative arrangements, the central office service unit disconnects PC 10 and dials back to access PC 10 in order to guard against tampering of the meter reading and device10 control process from unauthorized sources. This central office (C.O.) service unit 20 is connected to a plurality of central office switches, such as switch 21 and 22 by utility telemetering trunks which are simple interoffice trunks. Each of the switches 21 and 22, which may be housed in different wire centres, has a switching network, 23 and 24, respectively, for transmitting communications signals, such as 15 voice signals, and including the meter reading and device control signals of this invention. Each of the switches comprises control processor means 26, operative under the control of a program 28, stored in memory 27 for controlling the operations of the switch. In response to signals received from PC 10, C.O. service unit 20 requests utility connections by sending signals similar to the kinds of signals 20 sent for setting up an interoffice call to the appropriate one of switches 21 or 22.
In this specific embodiment, the method used for sign~lling the request to be connected via a customer line to a particular metering interface unit (MIU) such as MIU 30, MIU 32 or MIU 35 is to send out a string of multifrequency (MF) digits. Such a string of digits usually consists of a key pulse 25 signal (KP), a four, five, seven or ten digit director number and a start (ST) signal.
In response to reception of these digits, a switch such as switch 21 translates the received directory number to identify a meter interface unit such as meter interface unit 30 and sets up a connection via a utility telemetry trunk (UTT), between the central office service unit 20, through a switching network 23 or 24, via a customer line to a MIU 30, 32 or35.
The utility telemetry trunk has a special class of service which identifies 5 to the connected switch that the requested connection is to be made with ringing suppressed. In response to a received directory number from a UTT, switch 21 sets up a connection with ringing suppressed to MIU 30. Note that a suppressed ringing connection differs from a conventional voice connection, not only in that a ringing signal is not sent and that the line is not monitored for a supervisory signal to stop or 10 "trip" ringing, but that no check is made that a ringing signal is actually flowing to the analog line. The ringing signal and its accompanying checks are a basic and inherent part of any normal telephone connection. For example, even when a facsimile call is completed, wherein no audible bell is heard, the circuits of the termin~ting facsimile machine respond to the ringing signal that is sent from the 15 switch.
When the suppressed ringing connection to the MIU has been established, MIU 30 is connected to C.O. service unit 20 and receives from that service unit or from PC 10 through the service unit an alert tone to trigger the MIU
into the telemetry mode. In accordance with the principles of this invention, wherein 20 a customer's station equipment includes both a voice or other co"~ llnication station and an MIU, the normal ringing signal alerts the co~ unication station, and, where this is a voice station, thereby alerts the customer, while the tone signal sent over the suppressed ringing connection alerts the MIU. Telemetry and control signals are then exchanged between C.O. service unit 20 or utility controller 10 and MIU 30 and 25 the data received from MIU 30 is tran~mitte-l from C.O. service unit 20 to PC 10 for processing by the utility. Similarly, utility control signals are sent from PC 10 to C.O. service unit 20 for transmi~sion to MIU 30 to control devices at the customer's home. If a customer picks up the handset of a telephone station while the comlllullication between the service unit and the meters and/or devices at the 30 customer's location is in progress, these comlllullications are quickly termin:~te~l and regular service restored to the customer. An incoming call, however, will receive a busy signal if a utility access call is in progress.
The UTT is a conventional in~lo~rlce trunk such as an E & M trunk or a common channel sign~ling trunk. Such trunks have arrangements whereby a change 35 of supervision at one end is signaled to the other end by a tone (E & M) or by an out of band tone or data signal. Such a trunk passes a supervisory signal, detected at a 20~3598 line circuit and passed by the switch processor to one end of the trunk, to the C.O.
service unit to effect a disconnect of that unit when a customer goes off-hook in the middle of a utility access call.
The C.O. service unit is expanded from prior art C.O. service units to be 5 connected by trunks to a plurality of switches, such as switch 21,...,22, and is connectable by a plurality of trunks (a trunk group) to each such switch. In some cases, several trunk groups may be connected to one switch, for example, to handle traffic to dirrelent groups of SLCs. The C.O. service unit is also connected to a plurality of utilities, only one of which is shown, which simultaneously establish 10 calls to dirrelent customers.
While in this embo~liment, the utility access unit PC 10 is connected to the MIU through a service unit, an ~lttorn~te configuration would permit a utility access unit to be connected via a trunk directly to the switching network for connection to the MIU.
The specific embodiment of FIG. 1 uses an analog line, tr~ncmitting voice band signals, ringing or tone alerting signals, and using direct cuIrent detection of supervision. The term "ringing" as used herein is used for convenience and because of its common use, but is meant to describe any process of customer alerting, including, for example customer tone alerting. For Integrated Services20 Digital Network (ISDN) lines, supervision and customer alerting signals are tr~n~mitte~l as data signals over the D-channel of the customer line.
FM. 1 shows details of a meter interface unit. A protection circuit 40 is used to protect the rest of the meter interface unit 30 against damage caused byelectrical signals carrying excessively high energy. Effectively, this is over-voltage 25 protection. Such protection circuits are well known in the prior art. Alert circuit 42 is used to detect the initial alerting tones used for signaling a request for a connection to the meter interf;lce co,..",l.nication circuit 46. The alert circuit continuously monitors the line when the line is on-hook in order to detect such signals. When such signals are detected, it activates the meter interface 30 conlll,ullication circuit which comlllunicates with PC 10 to exchange the reading information from meters and the control information on meters 50 and the controlinformation for controlling devices 48. When a control and/or reading cycle has been completed as determined by the C.O. service unit 20, the C.O. service unit goes on-hook which triggers switch 21 to send a 300 milli~econd minimllm open 35 loop signal to the MIU to signal a disconnect.
20~3598 In some cases, certain SLCs such as AT&T's SLC 96 will not transmit a forward disconnect (open). In many cases it will. It depends on the channel units installed. If the disconnect is not forwarded, then the MIU detects the end of data tr~n~mission and notifies the C.O. service unit during the data tr~n~mi~sion, and the 5 C.O. service unit detects the end of data tr~n~mi~ion and disconnects to connecting trunk. Depending on the channel unit inventory situation, the telephone service supplier may wish to allow off-hook tr~n~mi~sion. In this case, the MIU detects the end user off-hook signal in order to signal for a disconnect of the suppressed ringing connection. In any case, it is to provide the fol wal l disconnect through the 10 a~pl~pliate channel units.
As long as the meter interface unit 30 presents an impedance in excess of a~ v~inlately 10k ohms to the line, the central office will treat the line as being on-hook. If the customer should pick up his telephone instrument while the collllllullication between the PC and the meter interface unit is going on, switch 21 15 will detect the off-hook and cause the co,~ ication between the PC and the meter interface unit to be aborted by sending a disconnect signal to the MIU and an on-hook signal to the C.O. service unit to termin~te the connection.
Arrangements for col~ -icating with on-hook devices such as the meter in~erf~ce unit 30 are well known in the prior art and are defined, for example, 20 in Bellcore Technical Reference TR-TSY-000030, Issue 1, June, 1988.
FIGS. 2-6 are flow charts showing the call processing actions that take place while processing a utility telemetry call. FIG. 2 shows the first steps inresponse to a seizure from a utility telemetry trunk. As shown in FIG. 1, utility telemetry trunks, which are ordinary interoffice trunks, are connectable to different 25 switches. The trunk is originally in the idle state. It goes off-hook (actionblock 203) and a wink start signal is received from the trunk (action block 205).
This is followed by the digit reception state (action block 207). FIG. 3 is a flow chart in response to digit reception. If the trunk goes on-hook during or following digit reception (action block 311), the call is considered abandoned (action 30 block 313) and the trunk is taken down (action block 315) and restored to the idle state (action block 317). If there is a timeout or no digits are received as determined by the tests in the interdigit timing (test 321), then the call is considered abandoned (action block 341), the trunk is taken down (action block 343) and is restored to the idle state (action block 317). If the digits are properly received, the digits are 35 analyzed (action block 323). If the ST signal is the standard ST signal (ST0) as determined in test 325, the routing sequence 329 is entered. Otherwise, the type of alternate ST signal (STl, ST2, or ST3) is used to determine the length of a requested burst of ringing and this burst of ringing is requested for application after a connection has been set up to the requested meter interface unit. In this specific example, the length of the bursts are 20, 40 and 60 ms.; further experimentation may 5 indicate that other lengths, such as 50, 100 and 150 ms. may be preferable to take into account, for example, variations in the ability to control the length of a burst.
The best arrangement is to permit the length of the burst to be a pa~ elel controllable by the translation recent change facility of modern switches. If more than 3 different lengths (plus 0 length) are required, different groups of utility trunks 10 are used for different groups of ringing burst lengths; for example, group A could be used for 0, 20, 40 or 60 ms. bursts, while group B could be used for 0, 80, 100 and 120 ms. bursts. The burst of ringing is used in the SLC to assign a time slot for the connection to the customer's MIU, but is sufficiently short that it is completed before the connection is actually made; thus, no ringing signal is sent to the MIU.
15 Thereafter, the routing sequence 329 is performed. FIG. 4 is a flow diagram of the - steps of the routing sequence. First, a determination is made by test 401 whether the call is an inl~ witch call. If so, this indicates an error 403 since the utility telemetry trunk used on the call is supposed to be connected to the switch serving the requested meter interface unit. If this is not an inlel~wilch call, then test 405 determines 20 whether the called customer associated with the requested meter interface unit is busy or out of service. If so, then the busy or out of service status is returned to the trunk control program and further actions are performed as described in FM. 5. If the called customer line is not busy or out of service, then the connection is cut through if necessary with the abbreviated ring as derived in block 327 (action 25 block 409). When the call is cut through to the end user, a trunk off-hook signal is returned to the C.O. service unit 20. The trunk then goes into the telemetry data wait state (413). FM. 5 describes the actions performed if the called customer associated with the requested meter interface unit is busy or out of service (state 407). An on-hook signal is sent over the utility telemetering trunk to the C.O. service unit 20 30 (action block 501) and the trunk is taken down (action block 503). The trunk is then in the idle state (317).
In the telemetry data wait state, it is the responsibility of the C.O.
service unit, responsive to signals from the utility controller or internally triggered, to alert the MIU. Using today's equipment, the MIU is alerted by one of 13 single 35 frequencies. Once the MIU has been alerted, other signals such as frequency shift keyed data signals can be used for coll,-llullicating with the MIU. The end user 2~3598 cannot alert the MIU because the user's station equipment does not have a one-of-13 single frequency generator and, further, the call would be taken down if the end user went off hook.
FIG. 6 is a flow diagram of the actions performed in response to various 5 timeout conditions and in response to disconnect signals. The switch is in a wait state (413) during the telemetry connection. If a m~ximllm interval such as 10 or 20 seconds is exceeded (action block 611), the customer's line is disconnected and a signal is sent to the MIU to disconnect (action block 613), an on-hook signal is sent over the utility telem~t.-ring trunk to the C.O. service unit (action block 615) and that 10 trunk is taken down (action block 617) and restored to the idle state (317). The same disconnect functions are performed upon completion of a telemetry access call. Abilling record is then made in the same way as a billing record is made for a conventional (voice) call. If an on-hook signal is detected on the utility telemetering trunk, indicating a disconnect from the utility side (action block 621), then the line 15 connected to the metering interface unit is disconnected (action block 623), the utility telenle~ g trunk is sent an on-hook signal (action block 625), the trunk is taken down (action block 627), and restored to idle (317). If an overload or other condition is detected in the switch, indicating that telemet--ring activities should be temporarily suspended (action block 631), then the customer's line is disconnected 20 (action block 633), an on-hook signal is sent over the utility telemetering trunk (action block 635), that trunk is taken down (action block 637) and restored to the idle state (317). If the end user goes off-hook during the telemetering intervalbecause the end user wishes to place a call (action block 641), then the line is to be disconnected from the telemetering connection, a disconnect is sent from the switch 25 to the MIU (action block 643), the utility telemetering trunk is sent an on-hook (action block 645) and the trunk is taken down (action block 647). The end user is then prepared to be processed in the normal way by receiving dial tone and placing this call by dialing the appl~liate digits (state 649).
It is to be understood that the above description is only of one plt;rell~d 30 embodiment of the invention. Numerous other arrangements may be devised by one skilled in the art without departing from the scope of the invention. The invention is thus limited only as defined in the accompanying claims.
Technical Field This invention relates to a method and apparatus for accessing customer meters and for controlling customer devices over a telec~ mullications line.
5 Problem There has long been a need for reading utility meters periodically, a need which in the past has been met largely through manual arrangements. More recently, there has also been a growing desire by the electric power utilities to be able to control consumer electric loads as a means of forestalling brownout and 10 blackout situations. This need has been met with only partial success in the prior art by tel~,llc~e ing arrangements associated with telephone customer line access and by the use of carrier systems connected to power distribution lines. In these arrangements, utility meters at a telephone customer's home or business are accessed via the telephone customer's line when that line is not being used for telephone calls.
15 The method of accessing the line is to have a direct metallic path between the customer's meter reading interface and a service unit at the central of fice formonitoring and controlling the off-hook/on-hook supervisory state of the customer.
Access from the central office switch to the customer is provided through the use of a no-test trunk, i.e., a trunk which can access a customer's line even when that line is 20 already in the off-hook state. The trunk uses a no-test connection, i.e., a special metallic connection that bypasses the normal switched telephone connection and connects without making a busy test. This metallic connection passes direct current signal. The no-test trunk is used to get access to the meters without ringing the customer's line, the latter action being performed on all conventional telephone25 connections. The meter is then triggered to respond by being sent signals over the no-test connection, each signal consisting of a burst of tone of one of thirteenfrequencies in the telephone voice band. Using this arrangement, a connection isestablished to the customer's line, the service unit makes a test whether the customer is busy, and, if the customer is not busy, the service unit is connected to the 30 customer's meter interface. The meter interface is primed (alerted) by one of the thirteen frequencies to respond to data signals originating from the service unit or a controller at the utility, tr~nsmitted via the service unit. These data signals may be either in the form of dual tone multifrequency (DTMF) signals or frequency shiftkeyed binary data signals. Following the alerting of the meter interface unit, there is 35 an exchange of signaling information between the controller and the meter interface unit, the signaling exchange being used for triggering the reading of meters, for tr~n~mitting the present reading of the meters, for returning the present status of these meters, or for controlling a device such as an air conditioner at the called customer's residential or business location. The latter function allows a power S company to control its peak load by tempc,l~ily shutting down, possibly on a rotating basis, a portion of the air conditioners being served. The actual reading of the meters is performed by a reading mechanism that interfaces with the meter interface used. Meter status information includes indications of customer tampering, low battery, or other indic:ltions of a need for servicing. After a complete cycle of 10 meter readings and/or device control operations has been completed, the no-test connection is dropped and the customer is enabled to originate new calls.
While the customer's line is connected to the service unit, supervision of the customer's line is performed by the central office service unit (C.O. service unit) which is connected by a metallic access connection that provides current sensing15 supervision from a central office service unit. In modern digital switching systems, such as the SESS~) switch manufactured by AT&T, and described in The AT&T
Technical Journal, July/August 1985, no metallic access connection is provided through the voice network, so that a no-test trunk is required for monitoring direct current supervisory signals. If the customer's telephone station goes off-hook, a 20 direct current in excess of 20 milli~mperes is detected by the C.O. service unit and the central office service unit disconnects the telemetry call. In some cases, the supervision is p~lrolllled from the customer's meter interface unit which transmits a disconnect signal to the central office service unit to disconnect the telemetry call.
There are a number of disadvantages to this arrangement. The no-test 25 trunk is a facility available in very small numbers in a central office, the number being limited by the no-test access arrangements. No-test trunks are used primarily for checking on customers whose lines are reported as being busy for too long a time, making tests of the resistance between the two wires of a customer line, and manual testing of a line. In a typical switch, such as the SESS switch, only two no-30 test trunks are available in an entire switch, which may serve up to several hundredthousand customer lines. In a typical meter reading cycle the time required for meter readings and/or device control operations may vary from 10 to 20 seconds. Clearly, two no-test trunks are inadequate to serve the meter reading and device control needs of all the customers of the SESS switch. Further, the requirement for a direct 35 metallic path in order to provide current sensing supervision makes it difficult to access lines which are not connected directly to a switch but are connected through a 20~35g8 subscriber line carrier system, such as the SLC 96 (Subscriber Line Carrier) manufactured by AT&T, since such SLC systems do not provide a metallic path for a normal voice connection. Further, billing records for such no-test trunk calls are made separately from the billing records for voice or data calls, thus creating S a-lmini~trative problems. Further, in prior art arrangements, if a customer wishes to originate a call while the meter reading is taking place, there are some arrangements in which the customer is blocked until the reading is completed and other arrangements in which the customer is blocked for a period of 1 to 2 seconds until the no-test connection can be dropped.
Because of the small number of no-test trunks and limited no-test access, and the fact that the no-test trunks are needed for their primary intended purposes, the number of meters which may be monitored and devices which may be controlled is much smaller than the number of such meters and devices served by a typical large local central office. It is costly to add substantial numbers of extra no-15 test trunks, in a digital switch such as the SESS switch which does not provide a metallic access voice switching network, because the metallic access unit provided for such no-test trunks is expensive. A problem of the prior art, therefore, is that there is no arrangement available which permits a large central office, especially a digital central office which does not provide a direct metallic path for telephone 20 connections, to access a large number of meter reading and device control interfaces within a reasonable period over the customer lines connecting that central of fice to the telephone stations and the remote metering devices.
Solution The above problem is solved, in a departure from the prior art by 25 providing, for example, arrangements wherein a standard interoffice trunk, controllable by special soflw~ of the connected ~wilchi-lg system, is used for accessing, over an analog customer line, a customer's premises device such as a meter interface unit (MIU) from a data access device, such as a utility meter reader/device controller; this standard trunk is then connectable to the customer's 30 line via a suppressed ringing connection through the co~ nunication signal switching network, used, for example, for voice signals, in order to access the customer's analog line, connected to the MIU. Advantageously, such an arrangement makes it possible to use a plurality of circuits for accessing different meter interface units at the same time and without requiring additional expensive 35 specialized no-test trunks.
Modern digital switching systems, such as the SESS switch, do not provide a metallic connection that can pass direct current signals; metallic access facilities are expensive in digital switches because they bypass the digital network which is used for passing speech signals for telephone conversations. The switching S network need not provide a metallic access from the C.O. service unit to the line because supervision is detected at the line circuit, an interface between the switching network and the customer line, and is passed by the software controlled processors of the switch to the connected trunk, which passes supervision to the C.O. service unit.
Trunks such as the well-known E & M trunks or trunks using common channel 10 ~ign:~ling have arrangements for colllnlu-licating a change in supervisory state at one end to the other end of the trunk. These arrangements are used to transmit customer supervisory state changes to the C.O. service unit so that the unit may disconnect if a customer goes off-hook.
In the prior art, the only way of getting access to a customer's line using 15 the standard switching network or switch fabric was to ring the customer's line, and to monitor supervision from a line circuit in the switch. In a departure from the prior art, a new type of call connection is made in which ringing is suppressed in order to avoid alerting the customer; supervision is monitored by the switch and transmitted via the software controlled processors and trunk supervisory signal transport 20 techniques to a mo~ o~ g central office unit. The meter interface unit is alerted without ringing the customer's line from a connection through the standard switch fabric of the central of fice by providing a new class of service for calls from the utility, the new class of service being characterized by a connection made without such ringing. In this case, the class of service is a class of service of the caller and 25 affects the nature of the call being set up. The meter interface unit is alerted that a connection to the meter interface is desired by a tone sent to the interface unit by the C.O. service unit, or, altern~tively, by the utility controller through the service unit.
The interface unit receives these tones while in the on-hook state and processes them without sending an off-hook signal back to the central office.
Billing records are made in the normal way that billing records are made for calls through the switching network. Advantageously, this type of call connection can use the normal switch fabric for accessing a customer line, while also providing the absence of ringing necessary to access the meter interface unit without disturbing the customer, and while continuing to use normal customer supervision35 from the switch.
Present-day subscriber line carriers (SLCs) will not set up a connection unless they detect ringing. An exception to this rule is for a connection from a no-test trunk wherein a special tone is provided which is recognized by the subscriber line carrier and which will then provide a metallic bypass of the SLC. In accordance 5 with one aspect of the invention, when a meter interf~ce unit access call is set up through a subscriber line carrier, a brief burst of ringing is applied on that connection. In response to that brief burst of ringing, the subscriber line carrier sets up a connection within its own switch fabric to the called customer whose meter interface unit is being accessed. The burst of ringing is sufficiently short that the 10 subscriber line carrier which repeats any ringing signals that it detects on its input, will not in fact repeat any ringing signal to that customer's line, thus, avoiding disturbing the customer when only the meter interface unit is being accessed.
A central office service unit interfaces between a utility controller, such as a personal ColllpuLt;l, at the utility and the meter interface unit connected through 15 the voice signal switching network. Responsive to signals from the utility controller, the central office service unit signals the switch with the identification of the called customer to set up a suppressed ringing connection to the desired meter interface unit. The central office service unit or utility controller transmits alerting signals to the meter interface unit. The central office service unit detects off-hook signals from 20 the switch in order to signal for a premature disconnect, and responds to a meter interface unit disconnect signal to signal the switch for a disconnect of the meter reading and/or device control connection. The central office service unit has a plurality of interorrlce trunks for co,~ icating with customers connected to other switching systems and for collullunicating simlllt~neously for reading several meters 25 in parallel for customers in these switching systems; it also is connectable to a plurality of utilities for simultaneous use over different trunks.
In accordance with one aspect of the invention, for an Integrated Services Digital Network (ISDN) station connected via a Primary Rate Interface or a Basic Rate Interface, and a digital line, the D-channel is used for colllnlullicating 30 with the meters and controllable devices. This also permits the comlliullication signal switching network to be used for providing access to the customer's lines and allows the high bandwidth (64 or 16 kb./sec.) D-channel to be utilized for col~ lunications with the meters and devices. Here, supervision is detected at the customer premises and is tr~n~mitted by data signals over the D-channel.
-6- 20Q~3~j98 Accordingly, this invention provides a method and apparatus for accessing customer premises devices from a data access device by using a suppressed ringing connection through a voice signal switching network of a teleco~ unications switching system.
S In accordance with one aspect of the invention there is provided atelephone switching system comprising: a switching network for interconnecting amultiplicity of telecommunications trunks and another multiplicity of analog customer lines; at least one of said trunks connectable to a utility data accessing device for accessing a customer premises device; and processor means operative under the control of a program for translating a class of service of said at least one of said trunks, and responsive to said tr~nCl~ting~ for establishing a connection through said network without transmitting ringing signals to an analog customer line.
In accordance with another aspect of the invention there is provided a method of accessing a customer premises device from a data accessing device via a telecommunications switching system, said telecommunications switching system comprising a voice band signal switching network for switchably interconnecting multiplicities of inlets and multiplicities of outlets, said inlets for connection to interoffice telecollllllunications trunks, said outlets for connection to analogcustomer lines, the method comprising: determining that a class of service for an inlet connected to said data ~CCPscing device is a class of service requiring establishment of a suppressed ringing connection; establishing a suppressed ringing connection from said inlet to an outlet of said voice band signal switching network for connecting said data accessing device to an analog customer line connected to station equipment of a customer; and transmitting signals over said suppressed ringing connection for accPccing said customer premises device over said analog line from said data accessing device.
Brief Description of the Drawing FIG. 1 is a block diagram illustrating connections for accessing customer meters and devices; and FIGs. 2-6 are flowcharts of actions performed in setting up such connections and in accessing meters and devices.
P
- 6a - 20 ~35g8 Detailed Description FIG. 1 is a block diagram of the operation of applicant's invention.
A terminal such as a personal computer 10 at the office of a utility is connected by a line or connected over an interoffice trunk to a telephone switch 21. When an 5 access number is dialed and received from PC 10 in switch 21, a connection is set up to a central office service unit 20. The central service unit is located herein in a first central office that includes switching system (switch) 21. In alternative arrangements, the central office service unit disconnects PC 10 and dials back to access PC 10 in order to guard against tampering of the meter reading and device10 control process from unauthorized sources. This central office (C.O.) service unit 20 is connected to a plurality of central office switches, such as switch 21 and 22 by utility telemetering trunks which are simple interoffice trunks. Each of the switches 21 and 22, which may be housed in different wire centres, has a switching network, 23 and 24, respectively, for transmitting communications signals, such as 15 voice signals, and including the meter reading and device control signals of this invention. Each of the switches comprises control processor means 26, operative under the control of a program 28, stored in memory 27 for controlling the operations of the switch. In response to signals received from PC 10, C.O. service unit 20 requests utility connections by sending signals similar to the kinds of signals 20 sent for setting up an interoffice call to the appropriate one of switches 21 or 22.
In this specific embodiment, the method used for sign~lling the request to be connected via a customer line to a particular metering interface unit (MIU) such as MIU 30, MIU 32 or MIU 35 is to send out a string of multifrequency (MF) digits. Such a string of digits usually consists of a key pulse 25 signal (KP), a four, five, seven or ten digit director number and a start (ST) signal.
In response to reception of these digits, a switch such as switch 21 translates the received directory number to identify a meter interface unit such as meter interface unit 30 and sets up a connection via a utility telemetry trunk (UTT), between the central office service unit 20, through a switching network 23 or 24, via a customer line to a MIU 30, 32 or35.
The utility telemetry trunk has a special class of service which identifies 5 to the connected switch that the requested connection is to be made with ringing suppressed. In response to a received directory number from a UTT, switch 21 sets up a connection with ringing suppressed to MIU 30. Note that a suppressed ringing connection differs from a conventional voice connection, not only in that a ringing signal is not sent and that the line is not monitored for a supervisory signal to stop or 10 "trip" ringing, but that no check is made that a ringing signal is actually flowing to the analog line. The ringing signal and its accompanying checks are a basic and inherent part of any normal telephone connection. For example, even when a facsimile call is completed, wherein no audible bell is heard, the circuits of the termin~ting facsimile machine respond to the ringing signal that is sent from the 15 switch.
When the suppressed ringing connection to the MIU has been established, MIU 30 is connected to C.O. service unit 20 and receives from that service unit or from PC 10 through the service unit an alert tone to trigger the MIU
into the telemetry mode. In accordance with the principles of this invention, wherein 20 a customer's station equipment includes both a voice or other co"~ llnication station and an MIU, the normal ringing signal alerts the co~ unication station, and, where this is a voice station, thereby alerts the customer, while the tone signal sent over the suppressed ringing connection alerts the MIU. Telemetry and control signals are then exchanged between C.O. service unit 20 or utility controller 10 and MIU 30 and 25 the data received from MIU 30 is tran~mitte-l from C.O. service unit 20 to PC 10 for processing by the utility. Similarly, utility control signals are sent from PC 10 to C.O. service unit 20 for transmi~sion to MIU 30 to control devices at the customer's home. If a customer picks up the handset of a telephone station while the comlllullication between the service unit and the meters and/or devices at the 30 customer's location is in progress, these comlllullications are quickly termin:~te~l and regular service restored to the customer. An incoming call, however, will receive a busy signal if a utility access call is in progress.
The UTT is a conventional in~lo~rlce trunk such as an E & M trunk or a common channel sign~ling trunk. Such trunks have arrangements whereby a change 35 of supervision at one end is signaled to the other end by a tone (E & M) or by an out of band tone or data signal. Such a trunk passes a supervisory signal, detected at a 20~3598 line circuit and passed by the switch processor to one end of the trunk, to the C.O.
service unit to effect a disconnect of that unit when a customer goes off-hook in the middle of a utility access call.
The C.O. service unit is expanded from prior art C.O. service units to be 5 connected by trunks to a plurality of switches, such as switch 21,...,22, and is connectable by a plurality of trunks (a trunk group) to each such switch. In some cases, several trunk groups may be connected to one switch, for example, to handle traffic to dirrelent groups of SLCs. The C.O. service unit is also connected to a plurality of utilities, only one of which is shown, which simultaneously establish 10 calls to dirrelent customers.
While in this embo~liment, the utility access unit PC 10 is connected to the MIU through a service unit, an ~lttorn~te configuration would permit a utility access unit to be connected via a trunk directly to the switching network for connection to the MIU.
The specific embodiment of FIG. 1 uses an analog line, tr~ncmitting voice band signals, ringing or tone alerting signals, and using direct cuIrent detection of supervision. The term "ringing" as used herein is used for convenience and because of its common use, but is meant to describe any process of customer alerting, including, for example customer tone alerting. For Integrated Services20 Digital Network (ISDN) lines, supervision and customer alerting signals are tr~n~mitte~l as data signals over the D-channel of the customer line.
FM. 1 shows details of a meter interface unit. A protection circuit 40 is used to protect the rest of the meter interface unit 30 against damage caused byelectrical signals carrying excessively high energy. Effectively, this is over-voltage 25 protection. Such protection circuits are well known in the prior art. Alert circuit 42 is used to detect the initial alerting tones used for signaling a request for a connection to the meter interf;lce co,..",l.nication circuit 46. The alert circuit continuously monitors the line when the line is on-hook in order to detect such signals. When such signals are detected, it activates the meter interface 30 conlll,ullication circuit which comlllunicates with PC 10 to exchange the reading information from meters and the control information on meters 50 and the controlinformation for controlling devices 48. When a control and/or reading cycle has been completed as determined by the C.O. service unit 20, the C.O. service unit goes on-hook which triggers switch 21 to send a 300 milli~econd minimllm open 35 loop signal to the MIU to signal a disconnect.
20~3598 In some cases, certain SLCs such as AT&T's SLC 96 will not transmit a forward disconnect (open). In many cases it will. It depends on the channel units installed. If the disconnect is not forwarded, then the MIU detects the end of data tr~n~mission and notifies the C.O. service unit during the data tr~n~mi~sion, and the 5 C.O. service unit detects the end of data tr~n~mi~ion and disconnects to connecting trunk. Depending on the channel unit inventory situation, the telephone service supplier may wish to allow off-hook tr~n~mi~sion. In this case, the MIU detects the end user off-hook signal in order to signal for a disconnect of the suppressed ringing connection. In any case, it is to provide the fol wal l disconnect through the 10 a~pl~pliate channel units.
As long as the meter interface unit 30 presents an impedance in excess of a~ v~inlately 10k ohms to the line, the central office will treat the line as being on-hook. If the customer should pick up his telephone instrument while the collllllullication between the PC and the meter interface unit is going on, switch 21 15 will detect the off-hook and cause the co,~ ication between the PC and the meter interface unit to be aborted by sending a disconnect signal to the MIU and an on-hook signal to the C.O. service unit to termin~te the connection.
Arrangements for col~ -icating with on-hook devices such as the meter in~erf~ce unit 30 are well known in the prior art and are defined, for example, 20 in Bellcore Technical Reference TR-TSY-000030, Issue 1, June, 1988.
FIGS. 2-6 are flow charts showing the call processing actions that take place while processing a utility telemetry call. FIG. 2 shows the first steps inresponse to a seizure from a utility telemetry trunk. As shown in FIG. 1, utility telemetry trunks, which are ordinary interoffice trunks, are connectable to different 25 switches. The trunk is originally in the idle state. It goes off-hook (actionblock 203) and a wink start signal is received from the trunk (action block 205).
This is followed by the digit reception state (action block 207). FIG. 3 is a flow chart in response to digit reception. If the trunk goes on-hook during or following digit reception (action block 311), the call is considered abandoned (action 30 block 313) and the trunk is taken down (action block 315) and restored to the idle state (action block 317). If there is a timeout or no digits are received as determined by the tests in the interdigit timing (test 321), then the call is considered abandoned (action block 341), the trunk is taken down (action block 343) and is restored to the idle state (action block 317). If the digits are properly received, the digits are 35 analyzed (action block 323). If the ST signal is the standard ST signal (ST0) as determined in test 325, the routing sequence 329 is entered. Otherwise, the type of alternate ST signal (STl, ST2, or ST3) is used to determine the length of a requested burst of ringing and this burst of ringing is requested for application after a connection has been set up to the requested meter interface unit. In this specific example, the length of the bursts are 20, 40 and 60 ms.; further experimentation may 5 indicate that other lengths, such as 50, 100 and 150 ms. may be preferable to take into account, for example, variations in the ability to control the length of a burst.
The best arrangement is to permit the length of the burst to be a pa~ elel controllable by the translation recent change facility of modern switches. If more than 3 different lengths (plus 0 length) are required, different groups of utility trunks 10 are used for different groups of ringing burst lengths; for example, group A could be used for 0, 20, 40 or 60 ms. bursts, while group B could be used for 0, 80, 100 and 120 ms. bursts. The burst of ringing is used in the SLC to assign a time slot for the connection to the customer's MIU, but is sufficiently short that it is completed before the connection is actually made; thus, no ringing signal is sent to the MIU.
15 Thereafter, the routing sequence 329 is performed. FIG. 4 is a flow diagram of the - steps of the routing sequence. First, a determination is made by test 401 whether the call is an inl~ witch call. If so, this indicates an error 403 since the utility telemetry trunk used on the call is supposed to be connected to the switch serving the requested meter interface unit. If this is not an inlel~wilch call, then test 405 determines 20 whether the called customer associated with the requested meter interface unit is busy or out of service. If so, then the busy or out of service status is returned to the trunk control program and further actions are performed as described in FM. 5. If the called customer line is not busy or out of service, then the connection is cut through if necessary with the abbreviated ring as derived in block 327 (action 25 block 409). When the call is cut through to the end user, a trunk off-hook signal is returned to the C.O. service unit 20. The trunk then goes into the telemetry data wait state (413). FM. 5 describes the actions performed if the called customer associated with the requested meter interface unit is busy or out of service (state 407). An on-hook signal is sent over the utility telemetering trunk to the C.O. service unit 20 30 (action block 501) and the trunk is taken down (action block 503). The trunk is then in the idle state (317).
In the telemetry data wait state, it is the responsibility of the C.O.
service unit, responsive to signals from the utility controller or internally triggered, to alert the MIU. Using today's equipment, the MIU is alerted by one of 13 single 35 frequencies. Once the MIU has been alerted, other signals such as frequency shift keyed data signals can be used for coll,-llullicating with the MIU. The end user 2~3598 cannot alert the MIU because the user's station equipment does not have a one-of-13 single frequency generator and, further, the call would be taken down if the end user went off hook.
FIG. 6 is a flow diagram of the actions performed in response to various 5 timeout conditions and in response to disconnect signals. The switch is in a wait state (413) during the telemetry connection. If a m~ximllm interval such as 10 or 20 seconds is exceeded (action block 611), the customer's line is disconnected and a signal is sent to the MIU to disconnect (action block 613), an on-hook signal is sent over the utility telem~t.-ring trunk to the C.O. service unit (action block 615) and that 10 trunk is taken down (action block 617) and restored to the idle state (317). The same disconnect functions are performed upon completion of a telemetry access call. Abilling record is then made in the same way as a billing record is made for a conventional (voice) call. If an on-hook signal is detected on the utility telemetering trunk, indicating a disconnect from the utility side (action block 621), then the line 15 connected to the metering interface unit is disconnected (action block 623), the utility telenle~ g trunk is sent an on-hook signal (action block 625), the trunk is taken down (action block 627), and restored to idle (317). If an overload or other condition is detected in the switch, indicating that telemet--ring activities should be temporarily suspended (action block 631), then the customer's line is disconnected 20 (action block 633), an on-hook signal is sent over the utility telemetering trunk (action block 635), that trunk is taken down (action block 637) and restored to the idle state (317). If the end user goes off-hook during the telemetering intervalbecause the end user wishes to place a call (action block 641), then the line is to be disconnected from the telemetering connection, a disconnect is sent from the switch 25 to the MIU (action block 643), the utility telemetering trunk is sent an on-hook (action block 645) and the trunk is taken down (action block 647). The end user is then prepared to be processed in the normal way by receiving dial tone and placing this call by dialing the appl~liate digits (state 649).
It is to be understood that the above description is only of one plt;rell~d 30 embodiment of the invention. Numerous other arrangements may be devised by one skilled in the art without departing from the scope of the invention. The invention is thus limited only as defined in the accompanying claims.
Claims (19)
1. A telephone switching system comprising:
a switching network for interconnecting a multiplicity of telecommunications trunks and another multiplicity of analog customer lines;
at least one of said trunks connectable to a utility data accessing device for accessing a customer premises device; and processor means operative under the control of a program for translating a class of service of said at least one of said trunks, and responsive to said translating, for establishing a connection through said network without transmitting ringing signals to an analog customer line.
a switching network for interconnecting a multiplicity of telecommunications trunks and another multiplicity of analog customer lines;
at least one of said trunks connectable to a utility data accessing device for accessing a customer premises device; and processor means operative under the control of a program for translating a class of service of said at least one of said trunks, and responsive to said translating, for establishing a connection through said network without transmitting ringing signals to an analog customer line.
2. The switching system of claim 1 wherein tone signals are transmitted over said connection to alert a device at customer station equipment.
3. The telecommunications system of claim 1 wherein frequency shift keyed signals are transmitted over said connection for exchanging data with a device at a customer premises.
4. The telecommunications system of claim 1 wherein said processor means are further operative under the control of a program for making billing record of said connection, said process of making a billing record being essentially the same as a process for making a billing record of a voice call.
5. The telecommunications switching system of claim 1 wherein said processor means is further operative under the control of said program for detecting an off-hook signal from a customer station connected over said connection and responsive to a detection of said off-hook signal for disconnecting said connection.
6. A method of accessing a customer premises device from a data accessing device via a telecommunications switching system, said telecommunications switching system comprising a voice band signal switching network for switchably interconnecting multiplicities of inlets and multiplicities of outlets, said inlets for connection to interoffice telecommunications trunks, said outlets for connection to analog customer lines, the method comprising:
determining that a class of service for an inlet connected to said data accessing device is a class of service requiring establishment of a suppressed ringing connection;
establishing a suppressed ringing connection from said inlet to an outlet of said voice band signal switching network for connecting said data accessing device to an analog customer line connected to station equipment of a customer; and transmitting signals over said suppressed ringing connection for accessing said customer premises device over said analog line from said data accessing device.
determining that a class of service for an inlet connected to said data accessing device is a class of service requiring establishment of a suppressed ringing connection;
establishing a suppressed ringing connection from said inlet to an outlet of said voice band signal switching network for connecting said data accessing device to an analog customer line connected to station equipment of a customer; and transmitting signals over said suppressed ringing connection for accessing said customer premises device over said analog line from said data accessing device.
7. The method of claim 6 further comprising:
establishing a connection from said data accessing device to said inlet prior to said establishing said suppressed ringing connection.
establishing a connection from said data accessing device to said inlet prior to said establishing said suppressed ringing connection.
8. The method of claim 7 wherein said connection from said data accessing device is established over an interoffice trunk.
9. The method of claim 6 wherein said transmitting comprises transmitting tone signals.
10. The method of claim 6 wherein said transmitting comprises transmitting frequency shift keyed signals through said network.
11. The method of claim 6 further comprising:
establishing a connection between said data accessing device and a central office service unit, connectable to said network.
establishing a connection between said data accessing device and a central office service unit, connectable to said network.
12. The method of claim 11 wherein said establishing a connection between said data accessing device and said central office service unit comprises establishing a connection from said accessing device to said central office service unit over a customer line.
13. The method of claim 11 wherein a plurality of switches in different wire centers is connectable to said service unit.
14. The method of claim 11 further comprising the step of establishing a plurality of simultaneous suppressed ringing connections in one of said plurality of switches from said service unit to a plurality of customer stations.
15. The method of claim 6 further comprising the step of:
making a billing record for said suppressed ringing connection in essentially the same manner as making a billing record for a voice call.
making a billing record for said suppressed ringing connection in essentially the same manner as making a billing record for a voice call.
16. The method of claim 6 further comprising the step of:
detecting an off-hook signal on said suppressed ringing connection for disconnecting said suppressed ringing connection.
detecting an off-hook signal on said suppressed ringing connection for disconnecting said suppressed ringing connection.
17. The method of claim 6 wherein said establishing comprises establishing a connection for connecting to a meter interface unit.
18. The method of claim 17 wherein said meter interface unit is also connected to a controllable device and wherein said transmitting further comprises transmitting signals for controlling said controllable device over said connection.
19. A method of accessing a customer premises device from a data accessing device via a telecommunications switching system, said telecommunications switching system comprising a switching network for switchably interconnecting multiplicities of inlets and multiplicities of outlets, said inlets for connection to interoffice telecommunications trunks, said outlets forconnection to customer lines, the method comprising:
determining that a class of service for an inlet connected to said data accessing device is a class of service requiring establishment of a suppressed ringing connection;
establishing a suppressed ringing connection from said inlet to an outlet of said switching network for connecting said data accessing device to a customer line connected to station equipment of a customer; and transmitting signals over said suppressed ringing connection for accessing said customer premises device over said customer line from said data accessing device.
determining that a class of service for an inlet connected to said data accessing device is a class of service requiring establishment of a suppressed ringing connection;
establishing a suppressed ringing connection from said inlet to an outlet of said switching network for connecting said data accessing device to a customer line connected to station equipment of a customer; and transmitting signals over said suppressed ringing connection for accessing said customer premises device over said customer line from said data accessing device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002095668A CA2095668C (en) | 1990-08-31 | 1991-05-30 | Telemetry access arrangement |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/576,542 US5189694A (en) | 1990-08-31 | 1990-08-31 | Telemetry access arrangement |
| US576,542 | 1990-08-31 |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002095668A Division CA2095668C (en) | 1990-08-31 | 1991-05-30 | Telemetry access arrangement |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2043598A1 CA2043598A1 (en) | 1992-03-01 |
| CA2043598C true CA2043598C (en) | 1995-03-14 |
Family
ID=24304861
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002043598A Expired - Lifetime CA2043598C (en) | 1990-08-31 | 1991-05-30 | Telemetry access arrangement |
Country Status (10)
| Country | Link |
|---|---|
| US (1) | US5189694A (en) |
| EP (2) | EP0565211B1 (en) |
| JP (2) | JP2872458B2 (en) |
| KR (1) | KR0135508B1 (en) |
| AT (2) | ATE148972T1 (en) |
| CA (1) | CA2043598C (en) |
| DE (2) | DE69128426T2 (en) |
| ES (2) | ES2110565T3 (en) |
| HK (2) | HK119697A (en) |
| SG (1) | SG48707A1 (en) |
Families Citing this family (80)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5243644A (en) * | 1990-08-31 | 1993-09-07 | At&T Bell Laboratories | Telemetry access arrangement |
| AP316A (en) * | 1991-05-28 | 1994-02-28 | Tellumat Pty Limited | System for the provision of at least two reticulated utilities. |
| US5327488A (en) * | 1992-03-20 | 1994-07-05 | At&T Bell Laboratories | Remotely initiated telemetry calling system |
| AU668553B2 (en) * | 1992-03-20 | 1996-05-09 | At & T Corporation | Remotely initiated telemetry calling system |
| US5327484A (en) * | 1992-04-30 | 1994-07-05 | At&T Bell Laboratories | Calling system for short duration data transactions |
| US5359641A (en) * | 1992-12-22 | 1994-10-25 | Bellsouth Corporation | Telemetry system with suppressed ringing connection |
| US5363431A (en) * | 1992-12-22 | 1994-11-08 | Bell South Corporation | Visual message waiting indication in a telephone voice message system |
| US5521964A (en) * | 1992-12-22 | 1996-05-28 | Bellsouth Corporation | Visual message waiting indication in a telephone voice message system |
| US5394461A (en) * | 1993-05-11 | 1995-02-28 | At&T Corp. | Telemetry feature protocol expansion |
| US5509054A (en) * | 1993-05-11 | 1996-04-16 | At & T Corp | Communication switching system |
| US5434911A (en) * | 1993-06-04 | 1995-07-18 | M & Fc Holding Company, Inc. | Call in-bound remote reading and data collection system |
| WO1994029997A1 (en) * | 1993-06-04 | 1994-12-22 | M & Fc Holding Company, Inc. | Dial in-bound meter interface unit which derives its power from a telephone line |
| US5812647A (en) * | 1993-06-14 | 1998-09-22 | New North Media Inc. | Display based marketing message control system and method |
| US5818725A (en) * | 1993-08-11 | 1998-10-06 | First Pacific Networks | System for utility demand monitoring and control |
| US5805458A (en) * | 1993-08-11 | 1998-09-08 | First Pacific Networks | System for utility demand monitoring and control |
| US5528507A (en) * | 1993-08-11 | 1996-06-18 | First Pacific Networks | System for utility demand monitoring and control using a distribution network |
| US5583923A (en) * | 1994-04-13 | 1996-12-10 | British Telecommunications Public Limited Company | Telephony network having no-ring telemetry call aborted in favor of incoming telephony calls |
| WO1995028791A1 (en) * | 1994-04-19 | 1995-10-26 | British Telecommunications Public Limited Company | Telecommunications networks |
| US5535267A (en) * | 1994-04-22 | 1996-07-09 | Bellsouth Corporation | Telemetry system with improved verification of telemetry interface unit installation |
| US5452343A (en) * | 1994-06-28 | 1995-09-19 | At&T Corp. | Telemetry access arrangement |
| US5579381A (en) * | 1994-08-25 | 1996-11-26 | Northern Telecom Limited | Methods and apparatus for providing suppressed ringing access |
| AU735817B2 (en) * | 1994-09-27 | 2001-07-19 | British Telecommunications Public Limited Company | Remote access systems |
| US6073174A (en) * | 1994-09-27 | 2000-06-06 | Bristish Telecommunications | Remote access systems |
| AU3571595A (en) * | 1994-09-27 | 1996-04-19 | British Telecommunications Public Limited Company | Remote access systems |
| US5802172A (en) * | 1994-12-05 | 1998-09-01 | Independent Technologies, Inc. | Electronic lock for coin telephones |
| US5546452A (en) * | 1995-03-02 | 1996-08-13 | Geotel Communications Corp. | Communications system using a central controller to control at least one network and agent system |
| US5825849A (en) * | 1995-08-31 | 1998-10-20 | Lucent Technologies, Inc. | Loop-back test system using a suppressed ringing connection |
| US5677947A (en) * | 1995-08-25 | 1997-10-14 | International Teldata Corporation | Apparatus and method for operating a telephone line telemetry device in a multiple host environment |
| US5682422A (en) * | 1995-08-25 | 1997-10-28 | International Teldata Corporation | Apparatus and method for on-demand activation of telephone line telemetry devices |
| US5812656A (en) * | 1995-11-15 | 1998-09-22 | Lucent Technologies, Inc. | System for providing prioritized connections in a public switched network |
| US5802155A (en) * | 1995-11-15 | 1998-09-01 | Lucent Techologies Inc. | Method and apparatus for controlling regular and supressed ringing connections in a telecommunications network |
| US6401081B1 (en) * | 1995-11-20 | 2002-06-04 | Schlumberger Resource Management Services, Inc. | Modular object-based architecture for extensible master station software |
| US5930346A (en) * | 1996-10-17 | 1999-07-27 | Chen; Abraham Y. | Extended public switched telephone network architecture with enhanced subscriber control on call setup |
| US5999526A (en) * | 1996-11-26 | 1999-12-07 | Lucent Technologies Inc. | Method and apparatus for delivering data from an information provider using the public switched network |
| US5905784A (en) * | 1996-11-26 | 1999-05-18 | Lucent Technologies Inc. | Method for silently alerting inbound-only telemetry interface units |
| US5995598A (en) * | 1997-02-10 | 1999-11-30 | International Business Machines Corporation | Phone line LAN |
| US6396839B1 (en) * | 1997-02-12 | 2002-05-28 | Abb Automation Inc. | Remote access to electronic meters using a TCP/IP protocol suite |
| US7046682B2 (en) * | 1997-02-12 | 2006-05-16 | Elster Electricity, Llc. | Network-enabled, extensible metering system |
| US5901201A (en) * | 1997-05-14 | 1999-05-04 | Bellsouth Corporation | Switch-based line continuity verification method and system |
| US6219409B1 (en) | 1998-02-27 | 2001-04-17 | Sharegate, Inc. | Premises gateway and premises network interfaces for accessing subscriber premises equipment and communication networks using ring suppression |
| DE19809835C2 (en) * | 1998-03-02 | 2001-07-19 | Deutsche Telekom Ag | Targeted call selection "Distinctive Call" |
| RU2133557C1 (en) * | 1998-09-09 | 1999-07-20 | Лукин Александр Федорович | Structurized-entity telephone network and telephone communication system for remote structurized entity using this network |
| US5995601A (en) * | 1998-09-30 | 1999-11-30 | Lucent Technologies, Inc. | Automatic remote meter reading system and method employing selectable line interface |
| US6700902B1 (en) | 1998-10-19 | 2004-03-02 | Elster Electricity, Llc | Method and system for improving wireless data packet delivery |
| US6633637B1 (en) * | 1999-07-01 | 2003-10-14 | Lucent Technologies Inc. | Suppressed ringing connectivity |
| ATE503189T1 (en) | 1999-07-30 | 2011-04-15 | Telcordia Licensing Company Llc | METHOD AND SYSTEM FOR TRANSMITTING GENERAL DATA IN A PUBLIC TELEPHONE NETWORK |
| US6978313B1 (en) | 1999-07-30 | 2005-12-20 | Telcordia Technologies, Inc. | Method and system for transporting generic data messages over the public switched telephone network to customer premises equipment without establishing a call |
| US6389120B1 (en) | 1999-09-03 | 2002-05-14 | Lucent Technologies Inc. | Method and apparatus for multiple logical channel information delivery over multiple suppressed ringing physical channels |
| US6661881B1 (en) | 2000-02-15 | 2003-12-09 | Lucent Technologies Inc. | Method and system for controlling functional capabilities of a telephonic switch employing control and status messages |
| US6347135B1 (en) | 2000-05-02 | 2002-02-12 | Teldata, Inc. | Apparatus and method for powering a telephone-based inbound telemetry device |
| US6487282B1 (en) | 2000-07-31 | 2002-11-26 | Firstpoint Energy Corp. | Apparatus and method for an inbound telemetry device to sense telephone line status |
| US6598003B1 (en) | 2000-10-31 | 2003-07-22 | Rx Monitoring Services, Llc | Power and environmental condition monitoring system and method |
| US6687574B2 (en) | 2001-11-01 | 2004-02-03 | Telcordia Technologies, Inc. | System and method for surveying utility outages |
| US6867707B1 (en) | 2002-04-24 | 2005-03-15 | Elster Electricity, Llc | Automated on-site meter registration confirmation using a portable, wireless computing device |
| US7119713B2 (en) * | 2002-06-27 | 2006-10-10 | Elster Electricity, Llc | Dynamic self-configuring metering network |
| US7227350B2 (en) * | 2004-03-18 | 2007-06-05 | Elster Electricity, Llc | Bias technique for electric utility meter |
| US7315162B2 (en) * | 2004-03-18 | 2008-01-01 | Elster Electricity, Llc | Reducing power consumption of electrical meters |
| US7239250B2 (en) * | 2004-04-26 | 2007-07-03 | Elster Electricity, Llc | System and method for improved transmission of meter data |
| US7262709B2 (en) * | 2004-04-26 | 2007-08-28 | Elster Electricity, Llc | System and method for efficient configuration in a fixed network automated meter reading system |
| US7187906B2 (en) * | 2004-04-26 | 2007-03-06 | Elster Electricity, Llc | Method and system for configurable qualification and registration in a fixed network automated meter reading system |
| US20050251403A1 (en) * | 2004-05-10 | 2005-11-10 | Elster Electricity, Llc. | Mesh AMR network interconnecting to TCP/IP wireless mesh network |
| US20050251401A1 (en) * | 2004-05-10 | 2005-11-10 | Elster Electricity, Llc. | Mesh AMR network interconnecting to mesh Wi-Fi network |
| US7142106B2 (en) * | 2004-06-15 | 2006-11-28 | Elster Electricity, Llc | System and method of visualizing network layout and performance characteristics in a wireless network |
| US7176807B2 (en) * | 2004-09-24 | 2007-02-13 | Elster Electricity, Llc | System for automatically enforcing a demand reset in a fixed network of electricity meters |
| US7742430B2 (en) * | 2004-09-24 | 2010-06-22 | Elster Electricity, Llc | System for automated management of spontaneous node migration in a distributed fixed wireless network |
| US7702594B2 (en) * | 2004-09-24 | 2010-04-20 | Elster Electricity, Llc | System and method for automated configuration of meters |
| US7170425B2 (en) * | 2004-09-24 | 2007-01-30 | Elster Electricity, Llc | System and method for creating multiple operating territories within a meter reading system |
| US7327998B2 (en) * | 2004-12-22 | 2008-02-05 | Elster Electricity, Llc | System and method of providing a geographic view of nodes in a wireless network |
| US20060206433A1 (en) * | 2005-03-11 | 2006-09-14 | Elster Electricity, Llc. | Secure and authenticated delivery of data from an automated meter reading system |
| US20060224335A1 (en) * | 2005-03-29 | 2006-10-05 | Elster Electricity, Llc | Collecting interval data from a relative time battery powered automated meter reading devices |
| US7495578B2 (en) * | 2005-09-02 | 2009-02-24 | Elster Electricity, Llc | Multipurpose interface for an automated meter reading device |
| US7308369B2 (en) * | 2005-09-28 | 2007-12-11 | Elster Electricity Llc | Ensuring automatic season change demand resets in a mesh type network of telemetry devices |
| US20070147268A1 (en) * | 2005-12-23 | 2007-06-28 | Elster Electricity, Llc | Distributing overall control of mesh AMR LAN networks to WAN interconnected collectors |
| US7545285B2 (en) * | 2006-02-16 | 2009-06-09 | Elster Electricity, Llc | Load control unit in communication with a fixed network meter reading system |
| US7427927B2 (en) * | 2006-02-16 | 2008-09-23 | Elster Electricity, Llc | In-home display communicates with a fixed network meter reading system |
| US8073384B2 (en) * | 2006-12-14 | 2011-12-06 | Elster Electricity, Llc | Optimization of redundancy and throughput in an automated meter data collection system using a wireless network |
| US8320302B2 (en) * | 2007-04-20 | 2012-11-27 | Elster Electricity, Llc | Over the air microcontroller flash memory updates |
| NZ586190A (en) | 2007-12-26 | 2013-05-31 | Elster Electricity Llc | A utility meter network wherein meters can transmit electrical and other readings to a collector by using other meters as repeaters |
| US8525692B2 (en) * | 2008-06-13 | 2013-09-03 | Elster Solutions, Llc | Techniques for limiting demand from an electricity meter with an installed relay |
| US8203463B2 (en) | 2009-02-13 | 2012-06-19 | Elster Electricity Llc | Wakeup and interrogation of meter-reading devices using licensed narrowband and unlicensed wideband radio communication |
Family Cites Families (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| USRE29499E (en) * | 1970-10-13 | 1977-12-20 | Reliance Telecommunication Electronics Company | On premise telephone loop tester |
| GB1402986A (en) * | 1971-05-13 | 1975-08-13 | Kent Meters Ltd | Interrogation of remote stations |
| US3899639A (en) * | 1973-05-11 | 1975-08-12 | Edmonton City | System and method for reading remotely located meters |
| US3922492A (en) * | 1974-03-18 | 1975-11-25 | James Ray Lumsden | Remote meter reading transponder |
| US4008458A (en) * | 1975-09-05 | 1977-02-15 | Darco Telemetering Systems | Remote automatic reading system |
| US4048448A (en) * | 1976-02-19 | 1977-09-13 | Bell Telephone Laboratories, Incorporated | Multiparty telephone ringing |
| US4394540A (en) * | 1981-05-18 | 1983-07-19 | Timex Corporation | Remote meter reader and method for reading meters over non-dedicated telephone lines |
| US4540849A (en) * | 1983-06-08 | 1985-09-10 | International Teldata Ii Corp. | Meter interface unit for utility meter reading system |
| US4700380A (en) * | 1984-07-20 | 1987-10-13 | Om Ahuja | Solid state remote actuable switch |
| SE454561B (en) * | 1985-04-15 | 1988-05-16 | Gote Eskil Yngve Holmberg | ANIMAL FELLA, SPECIAL MUSFELLA |
| JPS61295748A (en) * | 1985-06-24 | 1986-12-26 | Hochiki Corp | Transmitter for meter inspection information |
| US4646342A (en) * | 1985-09-11 | 1987-02-24 | Itt Corporation | Test trunk access controller |
| DE3689263T2 (en) * | 1985-11-25 | 1994-04-28 | Alcatel Nv | TELEMETRY END STATION. |
| US4804957A (en) * | 1985-11-27 | 1989-02-14 | Triad Communications, Inc. | Utility meter and submetering system |
| US4691344A (en) * | 1986-01-21 | 1987-09-01 | Aquatrol Corporation | Low-powered remote sensor and telephone line transmitter |
| US4856047A (en) * | 1987-04-29 | 1989-08-08 | Bd Systems, Inc. | Automated remote telemetry paging system |
| US4852152A (en) * | 1987-10-19 | 1989-07-25 | 501 Neptune Information Systems | High impedance signal detection device |
| WO1989008959A1 (en) * | 1988-03-07 | 1989-09-21 | Telemetry Research Ii, Inc. | Method and apparatus for remote commodity transfer control and monitoring |
| IT1216672B (en) * | 1988-03-31 | 1990-03-08 | Meschi Ind Grafica | TELE-PRINTING WITH A USER INFORMATION TELEPHONE SYSTEM AND EQUIPMENT COMING FROM PUBLIC UTILITIES, OR SIMILAR, CONPOSSIBILITY OF INTERACTION AND ITS METHODS OF REALIZATION AND USE. |
| FR2631765B1 (en) * | 1988-05-20 | 1990-08-31 | Dolphin Integration Sa | TELEPHONE INTERFACE CIRCUIT |
-
1990
- 1990-08-31 US US07/576,542 patent/US5189694A/en not_active Expired - Lifetime
-
1991
- 1991-05-30 CA CA002043598A patent/CA2043598C/en not_active Expired - Lifetime
- 1991-08-21 KR KR1019910014387A patent/KR0135508B1/en not_active IP Right Cessation
- 1991-08-22 SG SG1995002228A patent/SG48707A1/en unknown
- 1991-08-22 ES ES93201689T patent/ES2110565T3/en not_active Expired - Lifetime
- 1991-08-22 DE DE69128426T patent/DE69128426T2/en not_active Expired - Lifetime
- 1991-08-22 EP EP93201689A patent/EP0565211B1/en not_active Expired - Lifetime
- 1991-08-22 AT AT91307733T patent/ATE148972T1/en not_active IP Right Cessation
- 1991-08-22 AT AT93201689T patent/ATE161135T1/en not_active IP Right Cessation
- 1991-08-22 ES ES91307733T patent/ES2097190T3/en not_active Expired - Lifetime
- 1991-08-22 DE DE69124650T patent/DE69124650T2/en not_active Expired - Lifetime
- 1991-08-22 JP JP3233760A patent/JP2872458B2/en not_active Expired - Fee Related
- 1991-08-22 EP EP91307733A patent/EP0474407B1/en not_active Expired - Lifetime
-
1996
- 1996-10-02 JP JP8279894A patent/JP2926012B2/en not_active Expired - Fee Related
-
1997
- 1997-06-26 HK HK119697A patent/HK119697A/en not_active IP Right Cessation
-
1998
- 1998-03-02 HK HK98101606A patent/HK1002640A1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| DE69128426D1 (en) | 1998-01-22 |
| JPH09181833A (en) | 1997-07-11 |
| KR0135508B1 (en) | 1998-04-27 |
| AU630302B2 (en) | 1992-10-22 |
| JP2926012B2 (en) | 1999-07-28 |
| ES2097190T3 (en) | 1997-04-01 |
| EP0565211A3 (en) | 1993-11-03 |
| SG48707A1 (en) | 1998-05-18 |
| CA2043598A1 (en) | 1992-03-01 |
| ES2110565T3 (en) | 1998-02-16 |
| HK1002640A1 (en) | 1998-09-04 |
| ATE148972T1 (en) | 1997-02-15 |
| JP2872458B2 (en) | 1999-03-17 |
| DE69124650D1 (en) | 1997-03-27 |
| EP0474407A1 (en) | 1992-03-11 |
| EP0565211B1 (en) | 1997-12-10 |
| DE69124650T2 (en) | 1997-05-28 |
| KR920005533A (en) | 1992-03-28 |
| ATE161135T1 (en) | 1997-12-15 |
| EP0565211A2 (en) | 1993-10-13 |
| US5189694A (en) | 1993-02-23 |
| DE69128426T2 (en) | 1998-04-02 |
| AU8175991A (en) | 1992-03-05 |
| JPH04246961A (en) | 1992-09-02 |
| EP0474407B1 (en) | 1997-02-12 |
| HK119697A (en) | 1997-09-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA2043598C (en) | Telemetry access arrangement | |
| US5394461A (en) | Telemetry feature protocol expansion | |
| US5243644A (en) | Telemetry access arrangement | |
| CA2177759C (en) | Transmission of a data message during silent intervals of ringing for selection of terminal equipment | |
| EP0566242B1 (en) | Remotely initiated telemetry calling system | |
| EP0767998B1 (en) | Telemetry access arrangement | |
| KR100298018B1 (en) | Communication exchange system to support remote measurement function | |
| US4644527A (en) | Interface unit for transferring voice and data signals | |
| EP0755602B1 (en) | Telemetry system | |
| KR19990064286A (en) | Telecommunication switch | |
| CZ228394A3 (en) | Method of telemetric transmission and apparatus for making the same | |
| JP2002534851A (en) | System and method for power limited call processing in a communication facility | |
| CA2095668C (en) | Telemetry access arrangement | |
| KR0135491B1 (en) | Telemetering access arrangement | |
| US6016339A (en) | Telecommunication network using signalling without activating alerting devices in consumer's premises | |
| JP3098355B2 (en) | No-ringing communication system for apartment houses | |
| Pearce | Interfacing | |
| JPH0327659A (en) | Communication system for plural non-telephone terminal by public telephone network | |
| JPH0541879A (en) | Analog terminal line concentrator | |
| JPH04313064A (en) | Automatic meter checking system | |
| GB2352115A (en) | Digital key telephone system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed | ||
| MKEC | Expiry (correction) |
Effective date: 20121202 |