CA2052498A1 - System for interfacing telephone sets with a centrex system - Google Patents
System for interfacing telephone sets with a centrex systemInfo
- Publication number
- CA2052498A1 CA2052498A1 CA002052498A CA2052498A CA2052498A1 CA 2052498 A1 CA2052498 A1 CA 2052498A1 CA 002052498 A CA002052498 A CA 002052498A CA 2052498 A CA2052498 A CA 2052498A CA 2052498 A1 CA2052498 A1 CA 2052498A1
- Authority
- CA
- Canada
- Prior art keywords
- centrex
- telephone
- telephone sets
- supervisory
- lines
- 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.)
- Abandoned
Links
- 230000002093 peripheral effect Effects 0.000 claims abstract description 17
- 230000004044 response Effects 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 5
- 238000006467 substitution reaction Methods 0.000 claims description 3
- 230000006870 function Effects 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000011664 signaling Effects 0.000 description 3
- 230000000007 visual effect Effects 0.000 description 3
- 230000000903 blocking effect Effects 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- SZKKRCSOSQAJDE-UHFFFAOYSA-N Schradan Chemical compound CN(C)P(=O)(N(C)C)OP(=O)(N(C)C)N(C)C SZKKRCSOSQAJDE-UHFFFAOYSA-N 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000002372 labelling Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q3/00—Selecting arrangements
- H04Q3/58—Arrangements providing connection between main exchange and sub-exchange or satellite
- H04Q3/62—Arrangements providing connection between main exchange and sub-exchange or satellite for connecting to private branch exchanges
- H04Q3/625—Arrangements in the private branch exchange
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M3/00—Automatic or semi-automatic exchanges
- H04M3/42—Systems providing special services or facilities to subscribers
- H04M3/42314—Systems providing special services or facilities to subscribers in private branch exchanges
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Astronomy & Astrophysics (AREA)
- General Physics & Mathematics (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Sub-Exchange Stations And Push- Button Telephones (AREA)
- Telephonic Communication Services (AREA)
- Structure Of Telephone Exchanges (AREA)
Abstract
ABTRACT
A system for interfacing telephone sets with a centrex system comprising peripheral circuits for interfacing telephone lines connected to telephone sets and centrex lines, a set handler connected to the peripheral circuits for connecting individual telephone lines and individual centrex lines, the set handler comprising apparatus for translating supervisory and control signals received from the telephone sets into supervisory and control signals of types recognizable by the centrex system, whereby a centrex call can progress as provided by the centrex system.
A system for interfacing telephone sets with a centrex system comprising peripheral circuits for interfacing telephone lines connected to telephone sets and centrex lines, a set handler connected to the peripheral circuits for connecting individual telephone lines and individual centrex lines, the set handler comprising apparatus for translating supervisory and control signals received from the telephone sets into supervisory and control signals of types recognizable by the centrex system, whereby a centrex call can progress as provided by the centrex system.
Description
FIELD OF THE INVENTION:
This invention relates to telephone systems and in particular to a system for providing centrex services and enhanced services to telephone sets which would otherwise not be able to properly interface with a centrex system or to use certain centrex services.
BACKGROUND TO THE INVENTION:
A centrex system which is connected to a central office has long been known to provide PABX and other types of features to subscribers. Typically there is a separate subscriber line from the centrex system to each telephone set. This provides non-blocking capability. In order to utilize the centrex system, specialized telephone sets are required which respond to the specialized centrex supervisory signals and which can transmit specialized supervisory signals to the centrex system. Such specialized tel~phone sets are therefore expensive.
If a group of subscribers wishes to have fewer features, or more features than those provided by the centrex system, yet to use the centrex system, this has not been feasible, since it is expensive to provide various grades of centrex telephone, and it has not heretofore been possible to provide centrex lines with service features more than those which are possible to be provided by the centrex system.
SUMMARY OF THE PRESENT INVENTION:
In accordance with the present invention, a system is provided for interfacing telephone sets with a centrex system which always accesses the centrex system. There is preferably one dedicated centrex line for each telephone set, and thus there is no blocking in the interfacing system. However the present invention provides the means to drive a variety of different telephone sets which have capabilities in .. : .
. .
.
This invention relates to telephone systems and in particular to a system for providing centrex services and enhanced services to telephone sets which would otherwise not be able to properly interface with a centrex system or to use certain centrex services.
BACKGROUND TO THE INVENTION:
A centrex system which is connected to a central office has long been known to provide PABX and other types of features to subscribers. Typically there is a separate subscriber line from the centrex system to each telephone set. This provides non-blocking capability. In order to utilize the centrex system, specialized telephone sets are required which respond to the specialized centrex supervisory signals and which can transmit specialized supervisory signals to the centrex system. Such specialized tel~phone sets are therefore expensive.
If a group of subscribers wishes to have fewer features, or more features than those provided by the centrex system, yet to use the centrex system, this has not been feasible, since it is expensive to provide various grades of centrex telephone, and it has not heretofore been possible to provide centrex lines with service features more than those which are possible to be provided by the centrex system.
SUMMARY OF THE PRESENT INVENTION:
In accordance with the present invention, a system is provided for interfacing telephone sets with a centrex system which always accesses the centrex system. There is preferably one dedicated centrex line for each telephone set, and thus there is no blocking in the interfacing system. However the present invention provides the means to drive a variety of different telephone sets which have capabilities in .. : .
. .
.
-2- 2~2~98 excess, or less than thoæe provided by the centrex system, and those excess capabilities can be handled and services provided by the present invention.
The capability of the present invention can S be modified or defined by use of a plug-in read only memory (ROM) cartridge, which cartridge can control the capability of the present invention to operate particular telephone sets. Therefore, for example, the present invention can be utilized to interface a capability tier of various digital telephone sets which are available, e.y. from Mitel Corporation, for example those having displays, those not having displays, those having soft keys (having variable functions indicated on a display), etc.
As a result, the present invention provides increased flexibility to the user and substantially reduced cost, since specialized expensive centrex telephone sets need not be used, and the level sf capability of centrex services may be invoked or changed to a level desired by the customer, without reference to the telephone company.
In addition, the present invention allows inexpensive tip and ring 2500 type lines to be used between the present invention and the centrex system, yet high capability telephone sets can be used because of the interpretation function to various supervisory signals provided by the present invention.
The loop length of the present invention to the centrex system may be e.g. 4-5 km, and an additional loop length from the present invention to the telephone set can be an additional 2-3 Xm. Thus a substantially incxeased loop length may be used ov~r that of normal centrex lines. Normal centrex lines have a limited loop length of e.g~ 2-3 km, due to specialized line interfaces required at the centrex and at the , , - :: ;
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The capability of the present invention can S be modified or defined by use of a plug-in read only memory (ROM) cartridge, which cartridge can control the capability of the present invention to operate particular telephone sets. Therefore, for example, the present invention can be utilized to interface a capability tier of various digital telephone sets which are available, e.y. from Mitel Corporation, for example those having displays, those not having displays, those having soft keys (having variable functions indicated on a display), etc.
As a result, the present invention provides increased flexibility to the user and substantially reduced cost, since specialized expensive centrex telephone sets need not be used, and the level sf capability of centrex services may be invoked or changed to a level desired by the customer, without reference to the telephone company.
In addition, the present invention allows inexpensive tip and ring 2500 type lines to be used between the present invention and the centrex system, yet high capability telephone sets can be used because of the interpretation function to various supervisory signals provided by the present invention.
The loop length of the present invention to the centrex system may be e.g. 4-5 km, and an additional loop length from the present invention to the telephone set can be an additional 2-3 Xm. Thus a substantially incxeased loop length may be used ov~r that of normal centrex lines. Normal centrex lines have a limited loop length of e.g~ 2-3 km, due to specialized line interfaces required at the centrex and at the , , - :: ;
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specialize.d centrex telephone sets, and high capability (specialized) lines. The present invention therefore increases the radius around the centrex systam in which centrex services may be provided~
S In accordance with the present invention, a system for interfacing telephone sets with a centrex system is comprised of peripheral circuits for interfacing telephone lines connected to telephone sets and for interfacing csntrex lines, a set handler connected to the peripheral circuits ~or connecting individual telephone lines and individual centrex lines, the set handler comprising apparatus for translating supervisory and/or control signals received from the telephone sets into supervisory and control signals of types recognizable by the centrex system, whereby a centrex call can progress as provided by the centrex system.
Preferably each telephone set is assigned and may be connected to a dedicated centrex line on a one to one basis.
The set handler may be comprised of apparatus for translating supervisory and/or control signals received from the telephone sets and for providing services to the telephone sets which are in addition to or in substitution ~or those provided by the centrex system in response thereto.
The present invention is pr~ferably comprised of apparatus for translating supervisory and/or control signals received from the centrex system and in response providing services to the telephone sets which are otherwise are not capable of being dealt with by the telephone sets.
The present invention may be comprised o~
apparatus for translating supervisory and/or control signals received from the centrex system and in response .~:'. ` ` . ,: ~
, , ,:
" 20~2~98 for providing services to the telephone sets which are in addition to or in replacement for those provided by the centrex system.
BRIEF INTRODUCTION TO THE DRAWINGS:
A better understanding of the invention will be obtained by reference to the detailed description below, in conjunction with the following drawings, in which:
Figure 1 is a basic block diagram of the invention, and Figure 2 is a more detailed block diagram of the invention.
DETAILED DESCRIPTION OF THE INVENTION:
Turning to Figure 1, a centrex system 1 is illustrated having various tip and ring lines 3, each of which is destined for use with an individual telephone set. These lines are terminated in an interface 5.
Subscriber lines 7 connect the interface to the respective telephone sets 9. A ROM 11 is preferably plugged into the interface 5, to define the characteristic level or types of service to be provided by interface 5.
In operation, a telephone set 9 will go off-hook. The hook switch closure associated with the off-hook condition is sensed in interface 5 and a corresponding hook switch closure expected on a line 3 which is dedicated to that telephone set is transmitted (appears on a line 3) to centrex 1 by interface 5 and is sensed therein. The subscriber line is connected to the centrex line 3. In return centrex 1 transmits dial tone on that line 3, which is passed through int~rface 5 to the telephone set 9 which has yone off-hook.
The subscriber which is associated with the off-hook telephone set now dials for example a seven digit number which is passed through to centrex 1.
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-s- ~52~8 Interface 5 also monitors any signalling from the telephone set 9 which i5 non-standard for the centrex.
For example, the centrex will normally provide a hold, a conference call, or other services which are invoked by signalling directly from the telephone set 9~ However if the telephone set 9 provides a slgnal which is non-standard from centrex 1, interface S will detect it and replace it with the signal expected by the centrex 1.
This will often occur if the telephone set is not a special centrex set.
Furthermore, interface 5 may provide services not normally provided by centrex 1, for example a local paging capability, the driving of soft keys including labelling of particular pushbuttons on the telephone sets on an associated display, etc. When a telephone set generates command signals to invoke such services, either automatically or upon a request for service signal resulting from depression of a specialized or predetermined pushbutton on the telephone set, interface ~0 5 can block those signals from being passed to the centrex 1, and provides the service, e.g. by transmitting control signals to the telephone set 9 and centrex system. For example if a local page is to be invoked, the interface should transmit a hold ~ignal to the centrex causing the centrex to place a hold on the line 3 and then it should connect the subscribar's handset to a local paging amplifier.
The services which may be provided to the subscribers can be defined and/or programmed in a plug-in memory module ROM 11, which controls whichtranslation features and which level of service may be provided. For example, if it is known that the telephone sets 9 do nvt contain displays, ROM 11 will control the interface 5 so that display control signals, e.g. to display calling or called line numbers, or soft ,: ~
. .
-'', '~ : ' '., , ~', key labels, are not generated and are not transmitted to the telephone sets either from the centrex or from the interface.
Figure 2 illustrates a block diagram of the S invention. Each of the centrex lines 3 and subscriber lines 7 is terminated in an appropriate line circuit, shown as PIC (peripheral interface circuit) 13 or ~5 respectively. Each peripheral interface circuit can contain several (e.g. four) line circuits, which provide four wire pairs, i.e. four tip and ring lines to the centrex system. The peripheral interface circuits 13 and 15 may be digital network interface circuits sold by Mitel Corporation under the product number MT8972B, described in the Mitel Digital Communications Handbook.
The peripheral interface circuits connect to the input and output time-divided lines of time-and-space division switch 17, referred to below as a DX
switch. This switch is described in U.S. Patent 4,510,597, issued April 9th, 1985, invented by Conrad Lewis. A DX switch which can be used in element 17 is sold by Mitel Corporation as the product type MT8980D or as product type MT8981D, which are also described in the aforenoted Handbook. In a successful prototype of the invention, DX switch 17 had eight time divided input and eight output lines (links), of which six of each were connected to corresponding peripheral interface circuits as shown in Figure 2. The remaining two input and output links were allocated to common control.
Forty-eight ports were provided, with a maximum capacity of 192 64 Kbps channels, providing a bandwidth of 12 Mbps. Bandwidth allocation was fixed, . ~
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7 X0~2~98 with sixteen channels allocated to each peripheral interface slot. The six periphsral links (each of which involves an input and an output line of the DX switch 17) are distributed to the forty~eight ports, with different ~rame pulses sent to each group of twenty-four in order to split the bandwidth in halfO This allows twenty-four ports to use all 12 Mbp3 of the bandwidth, or 2 Mbps/slot if required.
The remaining two input and output lines of DX
switch 17 as noted above are allocated to common control. An input line and an output line of the DX
switch are connected to an HDLC circuit 19, and an input line and an output line of the DX switch are com~ected to a digital signal processor circuit DSP 21. An ASIC
digital signal processor 21 generates signals and decodes signals under control of microprocessor 29.
ASIC 23 is also connected to the HDLC circuit 19 and to one of the common control lines of DX switch 17. Inputs from the peripheral interface circuits are connected to ASIC 23 and to phase locked loop 25.
Phase locked loop 25 receives timing information from the interface circuits 13 receiving digital signals from lines 3, and provides synchronization signals to ASIC 23 for detection by microprocessor 29. Microprocessor 29 can thus synchronize outgoing siynals with those detected networX
signals.
Data and address buses 27 are connected to ASIC 23. A microprocessor 29, preferably type 68000 available from Motorola, Inc., random access ~emory 31 and ROM 11 are connected to bus ~7. ROM 11 is connected to the bus via an externally accessible connector. ROM
ll contains the programs accessed by microprocessor 29 in a well known manner to control operation of the DX
switch 17, digital signal processor 21, and ASIC 23. If . . -, . .
, : :
; not designated in another manner, ROM 11 contains a map of correlation of centrex lines to designated subscriber lines.
Operation of the circuit is as follows.
Assume that there is an incoming call from the centrex system on a line 3. The line circuit in PIC 13 receives ringing, which is detected and a ringing present signal is sent via DX switch 17. Microprocessor 29, reading the DX switch 17, recognizes that a ringing signal has been received on a particular line, accesses a program in ROM 11 and then sends a signal v.ia ASIC 23 which decodes the latter signal, and sends a command signal to DX switch 17 via the common control line to peripheral interface circuit 13 to send a local ringing control signal from DSP 21 to the designated, dedicated telephone set connected to one of lines 7 for that incoming line 3 via its associated interface circuit 15.
While other telephone sets can be used, it will be assumed for this disclosure that the telephone set used in MITELTM SUPERSET 420TM~
When the subscriber answers and goes off-hook, this is detected in its associated line interface ; circuit 15, which sends an off-hook signal to HDLC l9, which encodes it and sends a signal to microprocessor 29. Microprocessor 29 accesses a program in ROM 11 and ~ sends a control signal to the telephone set, which :~ signal is decoded in HDLC 19 and is sent via the control : input of DX switch 17 through the associated peripheral interface 15 and line 7 to turn on the telephone set microphone and earpiece. The microprocessor 29 also sends a message to the peripheral interface 13 associated with the incoming line 3 to terminate the ,:~
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loop to the centrex system. This causes the ringing signal at the centrex line to cease.
The microprocessor 29 then instructs the DX
switch 17 to connect a two way voice channel between the S incoming line 3 and the called line 7. A voice or low data rate data communication may now proceed.
If a subscriber, during the call, would like to use a feature, he pushes a feature key or soft key on his telephone set. The line 7 is monitored by the interface circuit 15, and in a manner just described, upon reception of the feature key or soft key switch closure ox other signal the interface circuit 15 sends a signal to HDLC 19 reflecting the operation of the feature key, and the HDLC translates this into a code understandable by microprocessor 29. The microprocessor then determines the appropriate action.
For example, if a hold or call transfer is desired, both of which can be effected at the centrex, the subscriber pushes a hold or transfer key on his telephone set. Since the key switch closure on the telephone set is likely not the signal expected by the centrex system since a non-centrex type phone is being used, the microprocessor, receiving a message via the HDLC that the particular feature or function is desired, causes the correct signalling to be sent to the centrex, e.g. a flash or a special DTMF code. ROM 11 carries a table of conversion codes which is accessed by the microprocessor 29 for the particular function requested.
Therefore, for example, if a subscriber pushes a key that requests a service commanded by a signal that the centrex expects as a flash, the microprocessor, in accessing the table, receives a conversion code which is an instruction to the interface 13 to perform a flash tthe line 3 current is briefly broken).
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- lo-The centrex system then responds by providing the service, e.g. by placing a hold on the line, transfer ring the line, etc. If the feature re~uest command conversion in ROM 11 is such that the centrex system 1 reyuires a DTMF code, the microprocessor 29 transmits a message, converted by ASIC 23, DSP 21 to create appropriate DTMF tones, which pass under control of microprocessor 29 through DX switch 17 into the output channel leading to the interface circuit 13 which is connected to the centrex line 3 in use.
The microprocessor 29 maintains track of each call in RAM 31. Therefore if the telephone sets connected in lines 7 have a display, such as the Mi-tel Corporation digital SUPERSET 420TM telephone set, microprocessor 29, using programs stored in ROM 11, can provide command signals to the telephone set, using the route and methods described above, so that a visual display of the status of the call or a visual display of the calling line number, or some other visual display is provided to the telephone in use.
The centrex system sometimes applies special ringing cadences, such as one long and three short rings, etc. for certain groups of telephone sets, or for certain purposes. The microprocessor 29 can detect and decode this specialized ringing and can either cause the telephone set to ring in the same cadence, or to merely ring normally, or can provide a special message to the telephone set display or cause the telephone set to operate in a special manner. If, instead of ringing, a tone signal is received from the centrex system, microprocessor 29 decode the tone in a similar manner described above provide information to the local telephone set to which it is directed.
The centrex system usually can provide services such as same number redial, redial busy , ;
:
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subscriber, speed dial, etc. The present invention can allow the subscribers connected to the present invention to avoid invoking those services at the centrex system, and to provide them instead. The m:icroprocessor 29 thus S accesses programs in ROM 11 to cause the redial of numbers which the microprocessor 29 has monitored as having already baen dialed, and has stored in R~M 31 whereby a same number redial or redial busy subscriber function may be invoked. Furthermore, RAM 31 can be used to store speed dial numbers which are dialed by the subscriber commanding them to be dialed by closing specialized speed dial switches on the telephone set.
Indeed, the subscriber by dialing specialized codes can store speed dial numbers at the centrex system, or at the circuit just described in RAM 31, or at both.
Whether this or other features are provided can depend on which operation programs are stored in plug in ROM ll, which can be purchased by the usPr to provide various grades of service. The present invention can thus be specifically programmed to interface different forms of centrex, or to provide different features for different forms of centrex on a telephone company by telephone company, feature group by feature group basis.
It will be understood that the present invention can be modified or expanded to interface normal telephone switching systems rather than or in addition to centrex systems, and with the addition of a switching system responsive to dialed digits, be used as a PABX or key telephone system.
Indeed, since the interface circuits 13 and 15 can communicate with the remainder of the circuit which may be referred to as a control complex by means of buses, the interface circuits may be grouped together with a power supply and separated Erom the control ' :. - : . '... ~ :
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20~2~98 complex. Groups of peripheral circuits with associat~d power supplies may be distributed around a building, connected to a communication bus wh:ich terminates at the control complex. This provides easy expandability of S the system, and application to the particular requirements of the particular group of sets of concern.
It will be recognized that the memory shown, RAM 31, ROM ll, may be utilized in various forms. For example, ROM ll may carry all of the normal operating and normal feature control programs for microprocessor 29 and be permanently connected to bus 27, while an auxiliary cartridge (not shown~ containing particular special feature control programs may be plugged into bus 27. Alternatively ROM ll can carry the normal operation programs for microprocessor 2g, a memory cartridge can be plugged in to provide special feature programs, and an additional application module can be added which contains programs specialized for the particular installation.
A person understanding this invention may now conceive of alternative structures and embodiments or variations of the above. All of those which fall within the scope of the claims appended hereto are considered to be part of the present invention.
.
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specialize.d centrex telephone sets, and high capability (specialized) lines. The present invention therefore increases the radius around the centrex systam in which centrex services may be provided~
S In accordance with the present invention, a system for interfacing telephone sets with a centrex system is comprised of peripheral circuits for interfacing telephone lines connected to telephone sets and for interfacing csntrex lines, a set handler connected to the peripheral circuits ~or connecting individual telephone lines and individual centrex lines, the set handler comprising apparatus for translating supervisory and/or control signals received from the telephone sets into supervisory and control signals of types recognizable by the centrex system, whereby a centrex call can progress as provided by the centrex system.
Preferably each telephone set is assigned and may be connected to a dedicated centrex line on a one to one basis.
The set handler may be comprised of apparatus for translating supervisory and/or control signals received from the telephone sets and for providing services to the telephone sets which are in addition to or in substitution ~or those provided by the centrex system in response thereto.
The present invention is pr~ferably comprised of apparatus for translating supervisory and/or control signals received from the centrex system and in response providing services to the telephone sets which are otherwise are not capable of being dealt with by the telephone sets.
The present invention may be comprised o~
apparatus for translating supervisory and/or control signals received from the centrex system and in response .~:'. ` ` . ,: ~
, , ,:
" 20~2~98 for providing services to the telephone sets which are in addition to or in replacement for those provided by the centrex system.
BRIEF INTRODUCTION TO THE DRAWINGS:
A better understanding of the invention will be obtained by reference to the detailed description below, in conjunction with the following drawings, in which:
Figure 1 is a basic block diagram of the invention, and Figure 2 is a more detailed block diagram of the invention.
DETAILED DESCRIPTION OF THE INVENTION:
Turning to Figure 1, a centrex system 1 is illustrated having various tip and ring lines 3, each of which is destined for use with an individual telephone set. These lines are terminated in an interface 5.
Subscriber lines 7 connect the interface to the respective telephone sets 9. A ROM 11 is preferably plugged into the interface 5, to define the characteristic level or types of service to be provided by interface 5.
In operation, a telephone set 9 will go off-hook. The hook switch closure associated with the off-hook condition is sensed in interface 5 and a corresponding hook switch closure expected on a line 3 which is dedicated to that telephone set is transmitted (appears on a line 3) to centrex 1 by interface 5 and is sensed therein. The subscriber line is connected to the centrex line 3. In return centrex 1 transmits dial tone on that line 3, which is passed through int~rface 5 to the telephone set 9 which has yone off-hook.
The subscriber which is associated with the off-hook telephone set now dials for example a seven digit number which is passed through to centrex 1.
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-s- ~52~8 Interface 5 also monitors any signalling from the telephone set 9 which i5 non-standard for the centrex.
For example, the centrex will normally provide a hold, a conference call, or other services which are invoked by signalling directly from the telephone set 9~ However if the telephone set 9 provides a slgnal which is non-standard from centrex 1, interface S will detect it and replace it with the signal expected by the centrex 1.
This will often occur if the telephone set is not a special centrex set.
Furthermore, interface 5 may provide services not normally provided by centrex 1, for example a local paging capability, the driving of soft keys including labelling of particular pushbuttons on the telephone sets on an associated display, etc. When a telephone set generates command signals to invoke such services, either automatically or upon a request for service signal resulting from depression of a specialized or predetermined pushbutton on the telephone set, interface ~0 5 can block those signals from being passed to the centrex 1, and provides the service, e.g. by transmitting control signals to the telephone set 9 and centrex system. For example if a local page is to be invoked, the interface should transmit a hold ~ignal to the centrex causing the centrex to place a hold on the line 3 and then it should connect the subscribar's handset to a local paging amplifier.
The services which may be provided to the subscribers can be defined and/or programmed in a plug-in memory module ROM 11, which controls whichtranslation features and which level of service may be provided. For example, if it is known that the telephone sets 9 do nvt contain displays, ROM 11 will control the interface 5 so that display control signals, e.g. to display calling or called line numbers, or soft ,: ~
. .
-'', '~ : ' '., , ~', key labels, are not generated and are not transmitted to the telephone sets either from the centrex or from the interface.
Figure 2 illustrates a block diagram of the S invention. Each of the centrex lines 3 and subscriber lines 7 is terminated in an appropriate line circuit, shown as PIC (peripheral interface circuit) 13 or ~5 respectively. Each peripheral interface circuit can contain several (e.g. four) line circuits, which provide four wire pairs, i.e. four tip and ring lines to the centrex system. The peripheral interface circuits 13 and 15 may be digital network interface circuits sold by Mitel Corporation under the product number MT8972B, described in the Mitel Digital Communications Handbook.
The peripheral interface circuits connect to the input and output time-divided lines of time-and-space division switch 17, referred to below as a DX
switch. This switch is described in U.S. Patent 4,510,597, issued April 9th, 1985, invented by Conrad Lewis. A DX switch which can be used in element 17 is sold by Mitel Corporation as the product type MT8980D or as product type MT8981D, which are also described in the aforenoted Handbook. In a successful prototype of the invention, DX switch 17 had eight time divided input and eight output lines (links), of which six of each were connected to corresponding peripheral interface circuits as shown in Figure 2. The remaining two input and output links were allocated to common control.
Forty-eight ports were provided, with a maximum capacity of 192 64 Kbps channels, providing a bandwidth of 12 Mbps. Bandwidth allocation was fixed, . ~
-': ' ; ', : ` ; '., .~
: , :, :, : ,: , , :
:: .- : , -:, :: . - , : : ~ :
,~ ,:, . :::
7 X0~2~98 with sixteen channels allocated to each peripheral interface slot. The six periphsral links (each of which involves an input and an output line of the DX switch 17) are distributed to the forty~eight ports, with different ~rame pulses sent to each group of twenty-four in order to split the bandwidth in halfO This allows twenty-four ports to use all 12 Mbp3 of the bandwidth, or 2 Mbps/slot if required.
The remaining two input and output lines of DX
switch 17 as noted above are allocated to common control. An input line and an output line of the DX
switch are connected to an HDLC circuit 19, and an input line and an output line of the DX switch are com~ected to a digital signal processor circuit DSP 21. An ASIC
digital signal processor 21 generates signals and decodes signals under control of microprocessor 29.
ASIC 23 is also connected to the HDLC circuit 19 and to one of the common control lines of DX switch 17. Inputs from the peripheral interface circuits are connected to ASIC 23 and to phase locked loop 25.
Phase locked loop 25 receives timing information from the interface circuits 13 receiving digital signals from lines 3, and provides synchronization signals to ASIC 23 for detection by microprocessor 29. Microprocessor 29 can thus synchronize outgoing siynals with those detected networX
signals.
Data and address buses 27 are connected to ASIC 23. A microprocessor 29, preferably type 68000 available from Motorola, Inc., random access ~emory 31 and ROM 11 are connected to bus ~7. ROM 11 is connected to the bus via an externally accessible connector. ROM
ll contains the programs accessed by microprocessor 29 in a well known manner to control operation of the DX
switch 17, digital signal processor 21, and ASIC 23. If . . -, . .
, : :
; not designated in another manner, ROM 11 contains a map of correlation of centrex lines to designated subscriber lines.
Operation of the circuit is as follows.
Assume that there is an incoming call from the centrex system on a line 3. The line circuit in PIC 13 receives ringing, which is detected and a ringing present signal is sent via DX switch 17. Microprocessor 29, reading the DX switch 17, recognizes that a ringing signal has been received on a particular line, accesses a program in ROM 11 and then sends a signal v.ia ASIC 23 which decodes the latter signal, and sends a command signal to DX switch 17 via the common control line to peripheral interface circuit 13 to send a local ringing control signal from DSP 21 to the designated, dedicated telephone set connected to one of lines 7 for that incoming line 3 via its associated interface circuit 15.
While other telephone sets can be used, it will be assumed for this disclosure that the telephone set used in MITELTM SUPERSET 420TM~
When the subscriber answers and goes off-hook, this is detected in its associated line interface ; circuit 15, which sends an off-hook signal to HDLC l9, which encodes it and sends a signal to microprocessor 29. Microprocessor 29 accesses a program in ROM 11 and ~ sends a control signal to the telephone set, which :~ signal is decoded in HDLC 19 and is sent via the control : input of DX switch 17 through the associated peripheral interface 15 and line 7 to turn on the telephone set microphone and earpiece. The microprocessor 29 also sends a message to the peripheral interface 13 associated with the incoming line 3 to terminate the ,:~
TM - Trade Mark ~, ' - :: :. ; ~ - : . .
,, , . !, . . , ~ , , .
loop to the centrex system. This causes the ringing signal at the centrex line to cease.
The microprocessor 29 then instructs the DX
switch 17 to connect a two way voice channel between the S incoming line 3 and the called line 7. A voice or low data rate data communication may now proceed.
If a subscriber, during the call, would like to use a feature, he pushes a feature key or soft key on his telephone set. The line 7 is monitored by the interface circuit 15, and in a manner just described, upon reception of the feature key or soft key switch closure ox other signal the interface circuit 15 sends a signal to HDLC 19 reflecting the operation of the feature key, and the HDLC translates this into a code understandable by microprocessor 29. The microprocessor then determines the appropriate action.
For example, if a hold or call transfer is desired, both of which can be effected at the centrex, the subscriber pushes a hold or transfer key on his telephone set. Since the key switch closure on the telephone set is likely not the signal expected by the centrex system since a non-centrex type phone is being used, the microprocessor, receiving a message via the HDLC that the particular feature or function is desired, causes the correct signalling to be sent to the centrex, e.g. a flash or a special DTMF code. ROM 11 carries a table of conversion codes which is accessed by the microprocessor 29 for the particular function requested.
Therefore, for example, if a subscriber pushes a key that requests a service commanded by a signal that the centrex expects as a flash, the microprocessor, in accessing the table, receives a conversion code which is an instruction to the interface 13 to perform a flash tthe line 3 current is briefly broken).
.. :.
. . ~,: .
- lo-The centrex system then responds by providing the service, e.g. by placing a hold on the line, transfer ring the line, etc. If the feature re~uest command conversion in ROM 11 is such that the centrex system 1 reyuires a DTMF code, the microprocessor 29 transmits a message, converted by ASIC 23, DSP 21 to create appropriate DTMF tones, which pass under control of microprocessor 29 through DX switch 17 into the output channel leading to the interface circuit 13 which is connected to the centrex line 3 in use.
The microprocessor 29 maintains track of each call in RAM 31. Therefore if the telephone sets connected in lines 7 have a display, such as the Mi-tel Corporation digital SUPERSET 420TM telephone set, microprocessor 29, using programs stored in ROM 11, can provide command signals to the telephone set, using the route and methods described above, so that a visual display of the status of the call or a visual display of the calling line number, or some other visual display is provided to the telephone in use.
The centrex system sometimes applies special ringing cadences, such as one long and three short rings, etc. for certain groups of telephone sets, or for certain purposes. The microprocessor 29 can detect and decode this specialized ringing and can either cause the telephone set to ring in the same cadence, or to merely ring normally, or can provide a special message to the telephone set display or cause the telephone set to operate in a special manner. If, instead of ringing, a tone signal is received from the centrex system, microprocessor 29 decode the tone in a similar manner described above provide information to the local telephone set to which it is directed.
The centrex system usually can provide services such as same number redial, redial busy , ;
:
: :; : : , - .
~ ., 2~2~9~
subscriber, speed dial, etc. The present invention can allow the subscribers connected to the present invention to avoid invoking those services at the centrex system, and to provide them instead. The m:icroprocessor 29 thus S accesses programs in ROM 11 to cause the redial of numbers which the microprocessor 29 has monitored as having already baen dialed, and has stored in R~M 31 whereby a same number redial or redial busy subscriber function may be invoked. Furthermore, RAM 31 can be used to store speed dial numbers which are dialed by the subscriber commanding them to be dialed by closing specialized speed dial switches on the telephone set.
Indeed, the subscriber by dialing specialized codes can store speed dial numbers at the centrex system, or at the circuit just described in RAM 31, or at both.
Whether this or other features are provided can depend on which operation programs are stored in plug in ROM ll, which can be purchased by the usPr to provide various grades of service. The present invention can thus be specifically programmed to interface different forms of centrex, or to provide different features for different forms of centrex on a telephone company by telephone company, feature group by feature group basis.
It will be understood that the present invention can be modified or expanded to interface normal telephone switching systems rather than or in addition to centrex systems, and with the addition of a switching system responsive to dialed digits, be used as a PABX or key telephone system.
Indeed, since the interface circuits 13 and 15 can communicate with the remainder of the circuit which may be referred to as a control complex by means of buses, the interface circuits may be grouped together with a power supply and separated Erom the control ' :. - : . '... ~ :
- ~
20~2~98 complex. Groups of peripheral circuits with associat~d power supplies may be distributed around a building, connected to a communication bus wh:ich terminates at the control complex. This provides easy expandability of S the system, and application to the particular requirements of the particular group of sets of concern.
It will be recognized that the memory shown, RAM 31, ROM ll, may be utilized in various forms. For example, ROM ll may carry all of the normal operating and normal feature control programs for microprocessor 29 and be permanently connected to bus 27, while an auxiliary cartridge (not shown~ containing particular special feature control programs may be plugged into bus 27. Alternatively ROM ll can carry the normal operation programs for microprocessor 2g, a memory cartridge can be plugged in to provide special feature programs, and an additional application module can be added which contains programs specialized for the particular installation.
A person understanding this invention may now conceive of alternative structures and embodiments or variations of the above. All of those which fall within the scope of the claims appended hereto are considered to be part of the present invention.
.
: . .. .
~ : ,:
. ~
Claims (10)
1. A system for interfacing telephone sets with a centrex system comprising:
(a) peripheral circuits, for interfacing telephone lines connected to telephone sets and centrex lines, (b) a set handler connected to the peripheral circuit for connecting individual telephone lines and individual centrex lines, (c) the set handler comprising means for translating supervisory and control signals received from the telephone sets into supervisory and control signals of types recognizable by the centrex system, whereby a centrex call can progress as provided by the centrex system.
(a) peripheral circuits, for interfacing telephone lines connected to telephone sets and centrex lines, (b) a set handler connected to the peripheral circuit for connecting individual telephone lines and individual centrex lines, (c) the set handler comprising means for translating supervisory and control signals received from the telephone sets into supervisory and control signals of types recognizable by the centrex system, whereby a centrex call can progress as provided by the centrex system.
2. A system as defined in claim 1, in which each telephone set is assigned and may be connected to a dedicated centrex line, on a one to one basis.
3. A system as defined in claim 1, in which the set handler is further comprised of means for translating supervisory and/or control signals received from the telephone sets and for providing services to the telephone sets which are in addition to or are in substitution for those provided by the centrex system.
4. A system as defined in claim 1, 2 or 3 in which the set handler is comprised of means for translating supervisory and/or control signals received from the centrex system and in response for providing services to the telephone sets which are otherwise not capable of being dealt with by the telephone sets.
5. A system as defined in claim 1, 2 or 3 in which the set handler is comprised of means for translating supervisory and/or control signals received from the centrex system and in response for providing services to the telephone sets which are additional to those provided by the centrex system.
6. A system as defined in claim 1, 2 or 3 in which the set handler is comprised of means for translating supervisory and/or control signals received from the centrex system and in response for providing services to the telephone sets which are in replacement for those provided by the centrex system.
7. A method of providing telephone service comprising interfacing telephone lines connected to telephone sets with centrex lines, translating supervisory and control signals received on the telephone lines from the telephone sets into supervisory and control signals of types recognizable by a centrex system, and applying the translated signal to the centrex lines whereby a centrex call can progress as provided by the centrex system.
8. A method as defined in claim 7 and the step of recognizing predetermined ones of the supervisory and control signals and providing services to the telephone sets which are in addition to or in substitution for those provided by the centrex system.
9. A method as defined in claim 7 including means for translating supervisory or control signals received from the centrex system and in response for providing services to the telephone sets which are in addition to those provided by the centrex system.
10. A method as defined in claim 7 including means for translating supervisory or control signals received from the centrex system and in response for providing services to the telephone sets which are in replacement for those provided by the centrex system.
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002052498A CA2052498A1 (en) | 1991-09-30 | 1991-09-30 | System for interfacing telephone sets with a centrex system |
| DE4232120A DE4232120A1 (en) | 1991-09-30 | 1992-09-25 | SYSTEM FOR INTERFACE CONNECTION OF TELEPHONE SETS WITH A CENTREX SYSTEM |
| ITMI922218A IT1255834B (en) | 1991-09-30 | 1992-09-25 | SYSTEM TO INTERFACE TELEPHONE DEVICES WITH A CENTREX SYSTEM |
| MX9205511A MX9205511A (en) | 1991-09-30 | 1992-09-28 | SYSTEM TO INTERCONNECT TELEPHONE DEVICES WITH A CENTREX SYSTEM |
| GB9220525A GB2260063A (en) | 1991-09-30 | 1992-09-29 | System for interfacing telephone sets with a centrex system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002052498A CA2052498A1 (en) | 1991-09-30 | 1991-09-30 | System for interfacing telephone sets with a centrex system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2052498A1 true CA2052498A1 (en) | 1993-03-31 |
Family
ID=4148471
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002052498A Abandoned CA2052498A1 (en) | 1991-09-30 | 1991-09-30 | System for interfacing telephone sets with a centrex system |
Country Status (5)
| Country | Link |
|---|---|
| CA (1) | CA2052498A1 (en) |
| DE (1) | DE4232120A1 (en) |
| GB (1) | GB2260063A (en) |
| IT (1) | IT1255834B (en) |
| MX (1) | MX9205511A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2081125C (en) * | 1992-10-22 | 1997-03-04 | Deborah L. Pinard | Portable telephone user profiles |
| AUPM940594A0 (en) * | 1994-11-11 | 1994-12-08 | Telecom Technologies Pty Ltd | Purpose-built centrex enhancing telephone system |
| DE19527815C1 (en) * | 1995-07-28 | 1996-10-17 | Siemens Ag | Mobile network emulator for private communication terminals |
| DE19846495A1 (en) * | 1998-10-09 | 2000-04-13 | Deutsche Telekom Ag | Network status information provision method for analogue connection lines |
-
1991
- 1991-09-30 CA CA002052498A patent/CA2052498A1/en not_active Abandoned
-
1992
- 1992-09-25 IT ITMI922218A patent/IT1255834B/en active IP Right Grant
- 1992-09-25 DE DE4232120A patent/DE4232120A1/en not_active Withdrawn
- 1992-09-28 MX MX9205511A patent/MX9205511A/en unknown
- 1992-09-29 GB GB9220525A patent/GB2260063A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| GB9220525D0 (en) | 1992-11-11 |
| ITMI922218A0 (en) | 1992-09-25 |
| IT1255834B (en) | 1995-11-17 |
| DE4232120A1 (en) | 1993-04-01 |
| GB2260063A (en) | 1993-03-31 |
| ITMI922218A1 (en) | 1994-03-25 |
| MX9205511A (en) | 1993-03-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |