JP2001326722A - System and method for controlling centrex service - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an exchange for a station house a multifunctional telephone set without analyzing the call control signals of multifunctional telephone sets. SOLUTION: This system is provided with adapters 38 and 39 attached between the multifunctional telephone sets 41 and 42 and ISDN basic speed interfaces 36 and 37, and speech communication channels 34 and 35 between the interfaces 36 and 37 and a digital transmission path 32, converts the voice channel signals and the control channel signals of the telephone sets 41 and 42 into two voice channels on the interfaces 36 and 37 with the adapters 38 and 39 and concentrates and transmits the two voice channels on/to the specified time slot of the transmission path 32 with semi-fixed connection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Centrex service control system and a control method thereof,
The present invention relates to a Centrex service control system capable of accommodating a multifunctional telephone without an office exchange analyzing a call control signal of the multifunctional telephone, and a control method therefor.

[0002]

2. Description of the Related Art Conventionally, a central exchange service in a central office exchange comprises a plurality of different central exchange user groups, central exchange subscribers belonging thereto, a communication line dedicated to the group, a special trunk, a special terminal, a group-specific number plan table, and a group. It consists of service data.

[0003] The Centrex service in the conventional central office exchange having such a configuration operates as follows. That is, when a Centrex subscriber dials out, the dialed digits are analyzed by the group-specific numbering plan table, and whether the call is an external call, an extension call to another subscriber in the same group, or a group-specific communication. It determines and processes whether it is an access call to a line / special trunk or an access call to a special terminal operated by a group-exclusive operator.

[0004] In addition to a service for giving permission of a service by referring to service data of individual Centrex subscribers, such as a call transfer service, a transfer destination when a group-exclusive operator is away from the desk is used. There is a service that can be given permission for a service based on group service data or the like. Further, there is a service which is permitted by giving permission with service data of each Centrex subscriber and replacing a terminal used by each Centrex subscriber with a special terminal. A caller ID display service is a typical example.

As described above, in the conventional central office exchange,
Various subscriber services and Centrex services have been newly added taking advantage of the electronic exchange system of the storage and storage system.

[0006]

However, in the above-mentioned prior art, since the required functions are too many, the market needs have been diversified in recent years, and it has become difficult to cope with all of these with a central office exchange. There was a problem that.

Further, since the PBX is treated as one user group, even if the inside of the PBX is divided into tenants, the central office connecting the relevant PBX cannot recognize each tenant inside the PBX. Therefore, there is a problem that the PBX, in which the latest technologies are gathered in the field of business communication, is an effective system for a large-scale user group, but is difficult to use for a small-scale user group. .

Further, by allocating the communication line between the central office exchange and the PBX to each tenant, it becomes possible to recognize the tenants inside the PBX by the central office exchange. For this user, there is a problem that the cost is increased due to having a dedicated line.

Accordingly, an object of the present invention is to provide a Centrex service system in which a central office exchange can accommodate a multifunctional telephone without analyzing a call control signal of the multifunctional telephone.

Another object of the present invention is to provide a Centrex service control system capable of changing a part of a Centrex subscriber realized by a conventional central office exchange to a multifunctional telephone.

[0011] Thus, in a Centrex service that is easy to use for small user groups, it is possible to replace some or all of the subscribers with a multifunction telephone controlled by a PBX, which is an advanced technology in the field of business communication. It becomes possible.

[0012]

In order to achieve the above object, a Centrex service control system according to the present invention comprises:
A Centrex service for controlling a Centrex service comprising an office exchange, a PBX connected to the office exchange by a digital transmission line, a multi-function telephone controlled by the PBX, and a Centrex subscriber controlled by the office exchange In a control system, an ISDN basic speed interface for connecting a multifunction telephone to a central office, an adapter mounted between the multifunction telephone and the ISDN basic speed interface, and a semi-permanent connection between voice channels of the ISDN basic speed interface. A voice channel signal of the multi-function telephone and a control channel signal are converted into two voice channels on the ISDN basic speed interface by the adapter, and are converted into two voice channels by the voice channel. Concentrator with a fixed connection by transmitting relative PBX, office exchange, without analyzing the call control signal of a multi-function telephone, characterized in that to be able to accommodate the enhanced phone.

[0013] The adapter preferably includes means for encoding and decoding the audio channel signal and the control channel signal into two audio channels on the ISDN basic rate interface.

Further, the central office exchange connects the two signals encoded and decoded by the adapter to a specific time slot of a digital transmission line connected to the PBX in a semi-fixed path, thereby concentrating a plurality of subscriber lines. , Preferably means for distribution to a single subscriber line.

Still further, the PBX is provided with means for distributing a signal of a specific time slot as a voice channel signal of a single multifunction telephone and a signal of a control channel, and concentrating signals of a plurality of multifunction telephones. preferable.

Another embodiment of the Centrex service control system according to the present invention is a central office exchange and a PB connected to the office exchange by an ISDN primary interface.
X, a multifunction telephone controlled by the PBX, and a user of the multifunction telephone controlled by the PBX in a Centrex service control system for controlling a Centrex service with a centralized subscriber controlled by a central office; The central office is provided with an extension interconnection means with other Centrex subscribers in the same Centrex group that is housed and controlled, and a part of the Centrex subscriber realized by the central office can be used as a multifunctional telephone. It is characterized by being able to.

Further, the central office exchange has means for determining and analyzing whether or not the call originates from a user belonging to a specific Centrex group based on the caller ID at the time of receiving the call setting signal from the subscriber of the ISDN primary interface. Is preferred.

Further, the central office exchange changes the called party number of the call setting signal to be transmitted when the subscriber of the ISDN primary rate interface to the subscriber by extension dialing from the Centrex subscriber is changed to an external number corresponding to the dialed extension number. It is preferable to provide a means for converting and setting.

Further, the PBX is provided with means for converting a called party number in a call setup signal received from a subscriber of the ISDN primary interface into a user group number and an extension number of a specific multi-function telephone and performing a receiving process. Is preferred.

Further, the PBX has a means for identifying whether the number dialed at the time of calling the user of the multi-function telephone is an external line call by an external line access number or an extension number dialing to a Centrex subscriber controlled by the central office exchange. Preferably, it is provided.

Still further, the PBX is used in the case of an extension dialing of a Centrex subscriber controlled by the central office exchange, and in the case of an external call by an external access number,
It is preferable to include a means for converting to an outside line number corresponding to the calling user and setting the same to the calling number in the call setting signal of the ISDN primary interface.

The Centrex service control method of the present invention is controlled by a central office switch, a PBX connected to the central office switch via a digital transmission line, a multifunctional telephone controlled by the PBX, and a central office switch. In a Centrex service control method for controlling a Centrex service with a Centrex subscriber, a voice channel signal and a control channel signal of a multifunctional telephone are encoded and decoded into two voice channels on an ISDN basic rate interface. And encoding,
Connecting the two decoded signals to a specific time slot of a digital transmission line connected to the PBX through a semi-fixed path, distributing a plurality of subscriber lines to a concentrator and a single subscriber line, Distributing the slot signal as a voice channel signal of a single multifunction telephone and a control channel signal, and concentrating signals of a plurality of multifunction telephones.

[0023]

Next, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the Centrex service control system of the present invention. This system comprises a digital transmission line 32 connected between the central office 1 and the PBX 2 as part of a subscriber line.
And the transmission device 31 on the PBX 2 side of the digital transmission line 32
A transmission device 33 on the central office 1, a specific time slot of the digital transmission line 32, and multifunction telephones 41 and 42.
Multifunction telephones 41 and 42 for connecting to the central office 1 ISDN basic speed interface 3 which is the nearest subscriber line
6,37, ISDN basic rate interface 36,3
7, the communication channels 34 and 35 semi-fixedly connected between the voice channels 7, the adapters 38 and 39 attached to the multi-function telephones 41 and 42, and the outgoing trunk and the incoming trunk connected between the central office 1 and the PBX 2. And a trunk 5.

The multi-function telephones 41 and 42 have a control channel in addition to the voice channel, and control of acceptance and release of a call is controlled by a control signal unique to the PBX2. This audio channel signal and the control channel signal are
The device for encoding and decoding the two audio channels on the N basic rate interfaces 36 and 37 is an adapter 3
8,39. The signals encoded and decoded by the adapters 38 and 39 pass through the transmission lines 31 to 37, and are analyzed and processed by the PBX 2 as signals from the multifunction telephones 41 and 42.

The subscriber controlled by the post-installed PBX 2 can form a plurality of user groups having different numbering plans, and install a switching board in each group.
Calls by extension number dialing within the same user group accommodated in the PBX 2 can be performed without the central office switch 1 performing call control. However, in the case of a call with a subscriber outside the group, it is necessary to go through an outgoing trunk and an incoming trunk connected between the PBX 2 and the central office 1. Although the same user group is used, one of the subscribers is controlled by the PBX 2 and the other is a subscriber of the Centrex controlled by the central office 1, which necessitates an extension interconnection.

Accordingly, another feature of the present invention is the extension connection enabling extension interconnection between a subscriber controlled by a post-installed PBX 2 and a Centrex subscriber directly accommodated and controlled by the central office 1. Is to provide a way.

FIG. 2 is a block diagram showing a detailed data structure of the extension interconnection method in the embodiment of the Centrex service control system according to the present invention. This extension interconnection method is a method of establishing an extension connection between a central office subscriber on the central office 1 side and a subscriber controlled by the post-installed PBX 2. Note that the central office exchange 1 and the PB
Outgoing trunk and incoming trunk 5 connected to X2
In the present invention, the ISDN primary rate interface (PR
I) Use 6. The central office switch 1 has subscriber data 11 of an ISDN primary rate interface (PRI) 6 and a Centrex group numbering plan table 14.
Subscriber Data 11 of Primary Rate Interface (PRI) 6
Includes an external line number-extension number conversion table 12. PB
X2 has a numbering plan table 21 for each user group, outgoing user subscriber data 22, and an outside line number-extension number conversion table 23.

Here, in the case of an extension call from a subscriber controlled by the post-installed PBX 2 to a Centrex subscriber controlled by the central office 1, from the numbering plan table 21 for each calling user group in the PBX 2, When it is determined that the dialed extension number needs to be routed to the outgoing trunk 5 for the central office 1, the PBX 2 extracts the corresponding external number from the outgoing user subscriber data 22 and sets up the call for the outgoing trunk 5. This is set as the caller number of the signal, and the extension number of the dialed Centrex subscriber at the central office 1 is set as the called party number and transmitted. Central office exchange 1 receiving a call setting signal from PBX 2
Obtains a Centrex subscriber group number 13 corresponding to the received call setup signal caller number from the outgoing line number-extension number conversion table 12 in the subscriber data 11 for each outgoing trunk, i.e., ISDN primary group interface, and The called party number in the call setting signal, that is, the extension number of the Centrex subscriber controlled by the central office 1 is analyzed according to the Centrex group number plan table 14, and the incoming call to the Centrex subscriber directly controlled by the central office 1 is received. Execute the process.

In the case of an extension originating from a Centrex subscriber controlled by the central office exchange 1 to a subscriber controlled by the PBX 2, the telephone is dialed from the number planning table 14 of the Centrex group in the central office exchange 1. Extension number is P
It is determined that the incoming call is to the ISDN primary group interface subscriber for BX2, and the central office exchange 1 uses the external number-extension number conversion table 12 in the subscriber data 11 for each ISDN primary group interface to obtain the dialed extension number. , And set and send it as the called party number in the incoming call setup signal to the ISDN primary interface subscriber. The PBX 2 that has received the call setting signal from the central office 1 sends the user group number 24 and the extension number (extension code) 25 corresponding to the called party number in the received call setting signal from the external number / extension number conversion table 23. This is analyzed according to the numbering plan table 21 of the user group in the PBX 2 and the incoming call to the multi-function telephone user controlled by the PBX 2 is executed.

[0031]

Next, an embodiment of the present invention will be described in detail with reference to the drawings.

First, a detailed configuration of the first embodiment of the Centrex service control system of the present invention will be described with reference to FIG. In this embodiment, the central office exchange 1 and the PB
X2, a digital transmission line 32 connected as a part of the subscriber line, a transmission device 31 on the PBX 2 side, a transmission device 33 on the central office 1 side, and a specific time slot of the digital transmission line 32. Multifunction telephones 41, 42, ISDN basic speed interfaces 36, 3 which are the nearest subscriber lines.
Communication channels 34 and 35 semi-fixedly connected between the voice channels 7 and the multifunction telephones 41 and 42 for connecting the multifunction telephones 41 and 42 to the central office 1 The ISDN basic speed interface which is the nearest subscriber line 36, 37, and an adapter 38 attached to the multifunction telephones 41, 42,
39, and an outgoing trunk and an incoming trunk 5 connected between the central office 1 and the PBX 2. The multi-function telephones 41 and 42 have a control channel separately from the voice channel, and the reception and release of the call are controlled by a control signal unique to the PBX2. The adapters 38 and 39 convert the audio channel signal and the control channel signal into ISD signals.
Means (means 1) for encoding and decoding two audio channels on the N basic rate interfaces 36 and 37 are provided.

The central office switch 1 is provided with the adapters 38 and 39.
The signals of the two audio channels on the ISDN basic rate interfaces 36 and 37 coded and decoded by
A means (means 2) for connecting a semi-fixed path to a specific time slot of the conventional digital transmission device 33 connected to the BX2 and distributing a plurality of subscriber lines to a concentrator line or a single subscriber line is provided.

The PBX 2 has means (means 3) for distributing or concentrating the signal of the specific time slot into the signal of the voice channel and the signal of the control channel of the plurality of multi-function telephones 41 and 42.

Next, the operation of the embodiment of the present invention will be described in detail with reference to the drawings.

First, the overall operation of this embodiment will be described in detail with reference to the block diagram of FIG. When one of the multi-functional telephone users 41 makes a call and dials the subscriber number of the other 42, the adapter 38 outputs a call setting signal as IS.
It is coded to a predetermined one of the two audio channels of the DN basic rate interface 36. Next, the semi-fixed path 34 set in advance by the central office 1
The signals of the two audio channels of the SDN basic rate interface 36 are condensed and transmitted in a predetermined time slot of the conventional digital transmission device 33 connected to the PBX 2.

Here, the time slots are time slot S1 and time slot S17. It is assumed that the signal of the voice channel of the multi-function telephone 41 is encoded in the time slot S1, and the signal of the control channel is encoded in the time slot S17. The call setting signal is distributed to the PBX 2 as an improved private branch exchange as a call setting signal of a specific subscriber by the digital transmission device 31 via the digital transmission line 32, and call processing is performed.

The PBX 2 analyzes the dialed digits in the call setup signal to recognize the other multi-function telephone user 42,
This time, incoming call processing is performed. In the incoming call processing of PBX2,
The incoming call setting signal is encoded in a specific time slot of the digital transmission device 31 and transmitted to the central office 1 via the transmission line 32.

The exchange 1 for the central office exchanges the information of the time slot determined by the conventional digital transmission device 33 connected to the PBX 2 by a preset semi-fixed path 35 into I
It is distributed and transmitted to two audio channel signals of the SDN basic speed interface 37. Here, it is assumed that the time slot is S2 and the time slot is S18.

It is assumed that the signal of the voice channel of the multi-function telephone user 42 is encoded in the time slot S2, and the signal of the control channel is encoded in the time slot S18. As a result, the incoming call setting signal is transmitted through the time slot S18 of the digital transmission device 33 and the semi-fixed path 35 to the ISDN
The signal is transmitted to one of the two audio channels of the basic speed interface 37.

Next, this signal is decoded by the adapter 39 as an incoming call signal to the multi-function telephone 42. When the multi-function telephone 42 responds, the response signal is encoded, transmitted, and decoded in a route reverse to the call setting signal, and transmitted to the multi-function telephone 41 on the calling side.

The special key signal of the multi-function telephone is
The control signal for turning on / off the special lamp of the multifunctional telephone is transmitted to the multifunction telephone in the same procedure as the call setting signal from the PBX2. .

Next, a second embodiment of the Centrex service control system of the present invention will be described in detail with reference to the drawings.

FIG. 3 is a block diagram showing the configuration of a second embodiment of the Centrex service system of the present invention. The second embodiment of the present invention comprises a central office exchange 1 and a PBX.
2; a multi-function telephone 4; its subscriber line 3; a Centrex subscriber accommodated in the central office 1; and a conventional communication line 6 between the central office 1 and the PBX 2. The conventional communication line 6 utilizes an ISDN primary interface.

The central office 1 uses the means 2 of the first embodiment described above and the caller ID at the time of receiving a call setup signal from a particular ISDN primary rate interface subscriber to make it correspond to a particular Centrex group. Means for determining whether the call is from a multi-function telephone user in the PBX 2 to which it belongs and analyzing the called party number according to the Centrex Group numbering plan (means 4); Means (means 5) for converting the called party number of the call setting signal to be transmitted when the call is received to the ISDN primary group interface subscriber into an external number corresponding to the dialed extension number (means 5).

The PBX 2 converts the called party number in the call setting signal received from the incoming trunk, ie, the ISDN primary interface, into the specific multifunctional telephone user group number and the extension number by the means 3 of the first embodiment. Means for performing incoming call processing (means 6), and the number dialed at the time of calling the multi-function telephone user is controlled by the internal exchange or the central office 1 by an external dial or an external line access number to another member in the same user group. Means (means 7) for identifying whether the call is an extension number of a Centrex subscriber, and to the calling user in the case of extension number dialing of the Centrex subscriber controlled by the central office 1 and in the case of an external call by an external line access number. The caller ID in the outgoing trunk, ie, the call setup signal of the ISDN primary interface, is converted to the corresponding external number. Means for setting a record containing (means 8).

Next, the operation of the second embodiment of the Centrex control system of the present invention will be described in detail with reference to FIG. When a call is made from the multi-function telephone 4 and the extension number of the Centrex subscriber is dialed, the extension number dialed by the means 7 from the numbering plan table specific to the originating user group is the extension number of the Centrex subscriber controlled by the central office 1. Then, an outgoing trunk from the PBX 2 to the central office 1, that is, the ISDN primary interface 6 is selected and a call setup signal is transmitted to it. At this time, the outside number corresponding to the calling user 4 is converted and set in the caller number information element by the means 8, and the dialed extension number is set as it is in the called number information element. When the central office exchange 1 receives the call setup signal via the incoming trunk, that is, the ISDN primary rate interface 6, the number set in the caller ID information element in the signal by the means 4 is assigned to the PBX belonging to the specific Centrex group.
2. Recognize that the user is a multi-functional telephone user within 2, analyze the called party number information element in the signal according to the Centrex group numbering plan, and receive the incoming called Centrex subscriber.

When a call is sent from the Centrex subscriber and the extension number of the multi-function telephone 4 is dialed, the central office exchange 1 uses the means 5 to indicate that the call is to the specific ISDN primary group interface subscriber 6 and that the call is transmitted at the time of the call termination. The called party number information element of the setting signal is converted and set to an outside line number corresponding to the dialed extension number. When the PBX 2 receives the call setup signal, the PBX 2 uses
The called party number information element in the call setting signal received from the SDN primary group interface 6 is converted into a specific multi-function telephone user group number and extension number, and the incoming call processing is performed.

[0049]

As described above, according to the present invention, according to the means 1 to 3, the signal of the voice channel and the signal of the control channel specific to the multifunction telephone are transferred to the two voice channels on the ISDN basic speed interface. Encoding and decoding are performed, and this is condensed and transmitted to the PBX through a semi-fixed path inside the central office exchange 1, and can be directly analyzed and processed as a signal from the multifunction telephone by the PBX. Therefore, there is an effect that the central office can accommodate the multifunctional telephone without analyzing the call control signal of the multifunctional telephone.

Further, the means 4 to 8 enable an extension mutual dial connection between a multifunction telephone user controlled by the PBX and another Centrex subscriber in the same Centrex group accommodated and controlled in the central office. Accordingly, there is an effect that a part of the Centrex subscriber realized by the conventional central office exchange can be changed to a multifunctional telephone.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing an extension interconnection method in the embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a second exemplary embodiment of the present invention.

[Explanation of symbols]

1 Central office exchange 2 PBX 3 Subscriber line 31 Digital transmission device (PBX side) 32 Digital transmission line 33 Digital transmission device (central exchange side) 34,35 Communication channel (semi-fixed path) 36,37 ISDN basic speed interface 5 Outgoing trunk / Incoming trunk 4, 41, 42 Multifunctional telephone 6 Conventional communication line 11 ISDN PRI subscriber data 12 External number-extension number conversion table (office exchange side) 13 Subscriber group number 14 Centrex group number plan 21 Numbering Plan for Each User Group 22 Outgoing User Subscriber Data 23 External Number-Extension Number Conversion Table (PBX Side) 24 External Code-User Group Number 25 Extension Code

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[Procedure amendment]

[Submission Date] April 18, 2001 (2001.4.1
8)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0002

[Correction method] Change

[Correction contents]

[0002]

2. Description of the Related Art Conventionally, a central exchange service in a central office exchange comprises a plurality of different central exchange user groups, a central exchange subscriber belonging thereto, a communication line dedicated to the group, a special trunk, a special terminal, a number plan table exclusive to the group, a group exclusive to the group. It consists of service data.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0003

[Correction method] Change

[Correction contents]

[0003] The Centrex service in the conventional central office exchange having such a configuration operates as follows. That is, when a Centrex subscriber dials out, the dialed digits are analyzed by the group-specific numbering plan table, and whether the call is an external call, an extension call to another subscriber in the same group, or a group-specific communication. Line / Special
It determines and processes whether it is an access call to a special trunk or a special terminal operated by a group-exclusive operator.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0042

[Correction method] Change

[Correction contents]

The signal of the special key of the multifunction telephone is
The control signal for turning on / off the special lamp of the multifunction telephone is transmitted to the PBX 2 in the same procedure as the call setting signal from the user, and transmitted to the multifunction telephone in the same procedure as the incoming call setting signal from the PBX 2. .

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5K024 AA62 BB10 CC03 DD01 DD04 DD05 EE01 GG01 GG03 5K049 BB02 BB04 BB13 BB23 CC03 CC05 CC06 CC07 DD04 FF01 FF11 FF12 FF38 5K051 BB01 CC04 DD01 DD13 EE01H18H10 KK

Claims (11)

[Claims] 1. An office exchange, a PBX connected to the office exchange by a digital transmission line, a multifunctional telephone controlled by the PBX, and a Centrex subscriber telephone controlled by the office exchange. A Centrex service control system for controlling a Centrex service, comprising: an ISDN for connecting the multi-function telephone to the central office exchange;
A basic speed interface; an adapter mounted between the multi-function telephone and the ISDN basic speed interface; and a communication channel semi-permanently connected between voice channels of the ISDN basic speed interface; The voice channel signal and the control channel signal of the multi-function telephone are converted into two voice channels on the ISDN basic rate interface, and the call channel is connected to the two voice channels by a semi-fixed connection. A Centrex service control system, characterized in that the central office exchange can accommodate the multi-function telephone by transmitting to the PBX without analyzing the call control signal of the multi-function telephone. 2. The adapter according to claim 1, further comprising means for encoding and decoding the audio channel signal and the control channel signal into two audio channels on the ISDN basic rate interface. The Centrex service control system according to claim 1. 3. The central office exchange connects the two signals encoded and decoded by the adapter to a specific time slot of the digital transmission line connected to the PBX in a semi-fixed path, and a plurality of subscriptions. 2. The centralized service control system according to claim 1, further comprising means for distributing subscriber lines to a concentrator and a single subscriber line. 4. The PBX includes means for distributing the signal of the specific time slot as a voice channel signal of the single multi-function telephone and a signal of a control channel, and concentrating signals of a plurality of subscriber lines. The Centrex service control system according to claim 1, wherein: 5. A central office exchange and an ISDN connected to the central office exchange.
A Centrex service control system for controlling a Centrex service, comprising a PBX connected by a primary rate interface, a multi-function telephone controlled by the PBX, and a Centrex subscriber telephone controlled by the central office switch, Extension exchange means for connecting a user of the multifunction telephone controlled by the PBX to another Centrex subscriber telephone in the same Centrex group accommodated and controlled by the central office, and realized by the central office. A part of the Centrex subscriber telephone set that has been used can be used as the multifunctional telephone set. 6. A means for determining and analyzing whether or not a call originates from a user belonging to a specific Centrex group based on a caller number at the time of receiving a call setup signal from a subscriber of the ISDN primary rate interface. The Centrex service control system according to claim 5, comprising: 7. The central office exchange transmits a called party number of a call setting signal to be transmitted when a subscriber of the ISDN primary group interface arrives at a subscriber by an extension dial from the Centrex subscriber telephone set, by using a dialed extension number. 6. The Centrex service control system according to claim 5, further comprising means for converting and setting an outside line number corresponding to the telephone number. 8. The PBX means for converting a called party number in a call setup signal received from a subscriber of the ISDN primary interface into a user group number and an extension number of a specific multi-function telephone and performing a receiving process. The Centrex service control system according to claim 5, comprising: 9. The PBX according to claim 1, wherein the number dialed at the time of calling the user of the multi-function telephone is an external call by an external line access number or an extension number dialing to a Centrex subscriber telephone controlled by the central office exchange. The Centrex service control system according to claim 5, further comprising means for identifying 10. The PBX is converted to an external number corresponding to the calling user in the case of extension number dialing of a Centrex subscriber telephone controlled by the central office exchange and in the case of an external line call by an external line access number. And the IS
6. The apparatus according to claim 5, further comprising means for setting a caller ID in a call setting signal of the DN primary interface.
The Centrex service control system according to 1. 11. An office exchange, a PBX connected to the office exchange by a digital transmission line, a multifunction telephone controlled by the PBX, and a Centrex subscriber telephone controlled by the office exchange. A Centrex service control method for controlling a Centrex service, comprising: encoding and decoding a voice channel signal and a control channel signal of the multifunction telephone into two voice channels on an ISDN basic rate interface. The two coded and decoded signals are connected to a specific time slot of the digital transmission line connected to the PBX by a semi-fixed path, so that a plurality of subscriber lines are concentrated and a single subscriber line is connected. Distributing the signal of the specific time slot to a voice channel of the single multifunction telephone. Signal and the distribution as a signal of the control channel, Centrex service control method characterized by including the step of concentrating the signals of a plurality of subscriber lines.