JP2761880B2 - Transmission control system for private branch exchange - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a transmission control method for a private branch exchange.

[Prior art] In recent years, ISDN (Integrated Server) that digitizes a communication network (telephone network) including a subscriber transmission section to improve the economy and quality of the network and provide various services.
ces Digital Network) is being envisioned, and its standardization work is being carried out by the CCITT (International Telegraph and Telephone Consultative Committee).

In the ISDN, the connection between the network and the terminal equipment on the user side is in the form of a bus. According to the current CCITT recommendations,
There are two types of user / network interfaces in N, a basic interface and a primary group interface.

FIG. 5 shows a configuration example on the user side when the basic interface is used.

In ISDN, a passive type main wiring bus MB is connected to a user side of a network terminating device NT1 which provides a basic interface for connecting a terminal device to a network.

The main wiring bus MB is connected to sockets ST1, ST2,.
The ISDN terminal devices TE1, TE2,..., TE8 are connected. Note that the maximum number of ISDN terminal devices that can be connected to these main wiring buses MB is eight.

The main wiring bus MB is physically a four-wire transmission line of two transmission / reception circuits, but has two information channels B1 and B2 (B channels) having a channel speed of 64 Kbps and a channel speed of 1 Kbps.
One signal channel D of 6 Kbps is multiplexed.

Here, the information channels B1 and B2 can be collectively used as one information channel of 128 Kbps, and one information channel can be divided into subchannel speeds of 32 Kbps, 16 Kbps, and 8 Kbps for use. Although limited, the D channel can be used as an information channel.

In addition, when one of the ISDN terminal devices is connected to the main wiring bus MB and a call request is made for the first time, another ISDN terminal device connected to the same main wiring bus MB newly establishes an ISDN network. At this time, unique identification information (terminal end point identifier: TEI) for the main wiring bus MB is set to the newly connected ISDN terminal device so that the connected ISDN terminal device can be reliably identified.

Therefore, for example, the ISDN terminal device TEI connected to the same main wiring bus MB, such as transmitting the information by calling the ISDN terminal device TE2 via the ISDN network.
1, TE2,..., TE8 can mutually transmit information, so that the use of the ISDN network can realize the extension call function without any special mechanism.

However, since such an extension call function uses the switching function of the ISDN network, there is a disadvantage that the extension call is charged by the ISDN network.

Therefore, in order to solve such inconvenience, it is conceivable to provide a private branch exchange between the network termination device NT1 and the main wiring bus MB. If the two information channels B1 and B2 are connected to each other and an extension call is made, there is a disadvantage that an incoming call from the ISDN network cannot be accepted.

As described above, up to eight ISDN terminal devices can be connected to the main wiring bus MB. However, if two ISDN terminal devices occupy the information channel for an extension call, the other
There is also a disadvantage that the ISDN terminal device cannot transmit information.

[Purpose] The present invention has been made to solve such disadvantages of the prior art, and has been made in consideration of an ISDN connected to the same main wiring bus.
It is an object of the present invention to provide a transmission control method of a private branch exchange that enables an appropriate extension call between terminal devices.

[Configuration] The present invention relates to a transmission control system for a private branch exchange that accommodates a plurality of ISDN terminal devices on the extension side. The information transmission between extensions is performed by allocating the information channel to each ISDN terminal device and allocating a sub-channel divided into fixed transmission capacities during communication. Is not performed at the time of transmitting information using an outside line, but is regarded as being performed at the time of transmitting information between extensions. Further, it is preferable that the transmission capacity allocated to the sub-channel is changed according to the terminal type of the ISDN terminal device that performs the inter-extension information transmission.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an ISDN communication system according to one embodiment of the present invention. In this figure, the same parts as those in FIG. 5 are denoted by the same reference numerals.

In the figure, between the network terminating device NT1 and the main wiring bus MB, the functions of the layer 1 protocol and all or a part of the functions of the layer 2 and 3 protocols are terminated for the ISDN terminal devices TE1 to TE8. A private branch exchange NT2 is provided.

In the above configuration, for example, when the operator of the ISDN terminal device TE1 forms a transmission file and makes an extension call for transmitting the transmission file to the ISDN terminal device TE2, the ISDN terminal device TE1 specifies the transmission destination by the operator. Then, as shown in FIG. 2, a call setting message S1 is sent to the private branch exchange NT2 to request the establishment of a communication path with the partner device, as shown in FIG.

At this time, in the call setup message S1, the address of the ISDN terminal device TE2 is set as the destination address, the information channel B1 is set as the requested channel, and the requested data rate (channel speed) is set at 32 Kbps.
In the following description, the exchange of messages for controlling the transmission procedure between the ISDN terminal device TE1 or the ISDN terminal device TE2 and the private branch exchange device NT2 is performed using the signal channel D.

At this time, the private branch exchange NT2 sends the call setup message S1
Since the destination address of the extension is specified, the vacant state of the requested information channel B1 on the extension side is checked, and if it is vacant, the private branch exchange NT2 sends the ISDN terminal device TE1 the upper 4 bits of the information channel B1. The lower 4 bits of the information channel B1 are allocated to the ISDN terminal device TE2.

Then, the private branch exchange NT2 assigns the lower 4 bits of the information channel B1 to be usable, and
Send a call setup message S2 to TE2. In addition, the private branch exchange device NT2 sends a call setting acceptance message S3 to the ISDN terminal device TE1, notifying that the call processing has been started and that the upper 4 bits of the information channel B1 have been allocated. With the upper 4 bits assigned, the information channel B1 is connected to the ISDN terminal device TE1.

Thus, when the ISDN terminal device TE2 starts a call, the ISDN terminal device TE2 sends a call message S4 to the private branch exchange device NT2. As a result, a call message S5 is sent from the private branch exchange NT2 to the ISDN terminal TE1.

When completing the incoming call operation corresponding to the call setting message S2, the ISDN terminal device TE2 sends a response message S6 for requesting / notifying the establishment of a communication path to the private branch exchange NT2.

As a result, the private branch exchange NT2 connects the information channel B to the ISDN terminal TE2 with the lower 4 bits allocated, and sends a response message S7 to the ISDN terminal TE1. The private branch exchange NT2 is an ISDN
A response confirmation message S8 is sent to the terminal device TE2.

Thus, the ISDN terminal device TE1 and the ISDN terminal device TE2
When a communication path is established between the
Information transmission S9 to the SDN terminal device TE2 is performed, whereby the transmission file of the ISDN terminal device TE1 is changed to the ISDN terminal device TE2.
Is transmitted to

In the information transmission S9, a transmission control procedure for information transmission set between the ISDN terminal device TE1 and the ISDN terminal device TE2 is performed, and the state of the information transmission at that time is shown in FIG. The data direction from the ISDN terminal devices TE1 and TE2 to the private branch exchange device NT2 is called “up”, and the opposite direction is called “down”.

In this case, the upper 4 bits of the information channel B1 are assigned to the ISDN terminal device TE1, and the lower 4 bits of the information channel B1 are assigned to the ISDN terminal device TE2.
TE1 sets the transmission data Ta in the upper 4 bits of the upstream side (hereinafter, referred to as an upstream information channel) UB1 of the information channel B1, and sets the upper 4 bits of the downstream side (hereinafter, referred to as a downstream information channel) DB1 of the information channel B1. Is taken in as received data Ra.

The ISDN terminal device TE2 sets the transmission data Tb in the lower 4 bits of the uplink information channel UB1, and captures the lower 4 bits of data in the downlink information channel DB1 as the reception data Rb.

Then, in the private branch exchange NT2, the information channels B1,
The B channel control unit CTB for controlling data exchange in B2 sets the upper 4 bits of the uplink information channel UB1 to the upper 4 bits of the downlink information channel DB1, and sets the lower 4 bits of the uplink information channel UB1 to the downlink information. By setting the upper 4 bits of channel DB1, ISDN terminal equipment TE1 and ISD
Information transmission is performed between the N terminal devices TE2.

The D channel control unit CTD is for performing signal control on the D channel in the private branch exchange NT2, and UB2 and DB2 indicate the upstream side and the downstream side of the information channel B2, respectively.

In this way, under the control of the private branch exchange device NT2, information transmission between the ISDN terminal device TE1 and the ISDN terminal device TE2 is performed using the information channel B1.

When the transmission of the transmission file is completed, the ISDN terminal device TE1
Sends a disconnection message S10 requesting release of the communication path to the private branch exchange NT2. As a result, the private branch exchange NT2
Sends a disconnection message S11 to the ISDN terminal device TE2.

In response, ISDN terminal device TE2 sends release message S12 for confirming release of the communication path to private branch exchange device NT2. As a result, the private branch exchange NT2 sends a release message S13 to the ISDN terminal TE1. As a result, ISDN
The communication path between the terminal device TE1 and the ISDN terminal device TE2 is released.

Further, the ISDN terminal device TE1 sends a release completion message S14 to the private branch exchange device NT2. Thereby, the private branch exchange N
T2 sends a release completion message S15 to the ISDN terminal device TE2.

 This terminates the call connection.

In the following procedure, a communication path is set between the ISDN terminal device TE1 and the ISDN terminal device TE2, and information transmission is performed according to a transmission control procedure set between the ISDN terminal devices TE1 and TE2. The communication path is released.

The details of the transmission procedure between the private branch exchange NT2 and the ISDN terminal equipments TE1 and TE2 and the transmission control procedure between the ISDN terminal equipments TE1 and TE2 are not directly related to the present invention, and therefore description thereof is omitted.

By the way, when the private branch exchange device NT2 makes the two ISDN terminal devices TE1 and TE2 accommodated in the extension perform an extension call in this way, the information channel B1 is exclusively used for the extension call, Information channel B2 is empty.

In this state, when an extension call is requested from another ISDN terminal device TE3 (to TE8), if the same extension call as described above is performed using the information channel B2 which is available at that time, 2
Since two information channels B1 and B2 are dedicated to extension calls,
When a call setup request is made from the SDN network, a connection response cannot be made to the ISDN network.

Therefore, when one information channel B1 is used for an extension call and another information channel B2 is idle and an extension call is requested from another ISDN terminal device, the request is not accepted. Is preferable.

However, even in this case, an outside line from another ISDN terminal device (ie, another ISDN terminal device connected to the ISDN network, etc.)
When the call setting request is made, the ISDN terminal device that has issued the call setting request causes the ISDN terminal device to use the information channel B2 at a data rate of 64 Kbps.

By the way, in the above-described embodiment, the private branch exchange NT2
However, since the extension calls are performed at a data rate of 32 Kbps, only one call can be made between the extensions. Therefore, if this extension call is performed at 16 Kbps, a two-way extension call can be realized using the information channel B1.

In this case, for example, if the ISDN terminal device TE1 requests an extension call to the ISDN terminal device TE2 at a data rate of 16 Kbps, as shown in FIG. 4, the private branch exchange device NT2 transmits the information channel B1 to the ISDN terminal device TE1. The first and second bits are respectively allocated to the third and fourth bits of the information channel B1 to the ISDN terminal device TE2.

As a result, the ISDN terminal device TE1 transmits the transmission data Ta.
Is set to the first and second bits of the information channel UB1, and the data of the first and second bits of the information channel B1 and the downlink information channel DB1 are taken in as the reception data Ra.

Further, the ISDN terminal device TE2 sets the transmission data Tb to the third and fourth bits of the uplink information channel UB1, and captures the third and fourth bits of data of the downlink information channel DB1 as reception data Rb.

Then, the B-channel control unit CTB of the private branch exchange NT2
Bits 1 and 2 of uplink information channel UB1 are assigned to downlink information channel
By setting bits 3 and 4 of DB1 and bits 3 and 4 of uplink information channel UB1 to bits 1 and 2 of downlink information channel DB1, the distance between ISDN terminal device TE1 and ISDN terminal device TE2 can be reduced. Is transmitted.

Thus, the ISDN terminal device TE1 and the ISDN terminal device TE2
Is performed using the upper 4 bits of the information channel B1, and the lower 4 bits of the information channel B1 can be used for an extension call of another ISDN terminal device.

In addition, the data rate assigned to internal calls is 8Kbps
, It is possible to make a four-way extension call using one information channel B1.

In the above-described embodiment, the call setting request is issued to the private branch exchange in a state where the data rate in the extension call is fixed and the data rate used by the ISDN terminal device requesting the extension is specified. By allowing the private branch exchange to specify the data rate in a call, the type of ISDN terminal device that requested the extension and the information channels B1, B2
The data rate assigned at the time of using an extension can be changed in accordance with the usage status of.

For example, an ISDN terminal device that requires a wide band when the information channel B1 is completely idle (for example,
A data rate of 32 Kbps is assigned when an extension is requested from a digital telephone), and a data rate of 8 Kbps is assigned when an extension is requested from a low-speed data terminal.

However, even in that case, when the number of information channels that can be allocated to an extension call is limited to one as described above, and when a part of the information channel B1 is already used for another extension call, An extension request from an ISDN terminal device requiring a large data rate that cannot be transmitted in the remaining portion of the information channel B1 can be prevented.

For example, 32Kbps of the data rate of information channel B1
Is being used, and 64
Extension requests from digital phones that require a Kbps data rate are rejected.

In the above-described embodiment, the number of information channels that can be assigned to an extension call is limited to one. However, two information channels B1 and B2 can be set so that they can be assigned to an extension call. However, in that case, the capacity of the extension call increases, but outside line connection from the ISDN network is rejected except when at least one information channel is completely free.

Further, in the above-described embodiment, the information channel assigned to the extension call is fixed to the information channel B1, but when the extension request is made, the information channel B2 is used for the call with the outside line. Can be assigned to an extension call.

Further, in the above-described embodiment, the case where the basic interface of ISDN is used is described. However, the present invention can be similarly applied to the case where the primary group interface of ISDN is used.

Also, the present invention is based on the
It can also be applied to systems that take DN compliance.

[Effects] As described above, according to the present invention, in a transmission control system of a private branch exchange that accommodates a plurality of ISDN terminal devices on the extension side, the extension between the ISDN terminal devices accommodated in the extension The information transmission is performed by interconnecting the extension lines, and the inter-extension information transmission is performed by each ISDN terminal device by dividing the information channel into sub-channels that are divided into fixed transmission capacities during communication. On the other hand, division of the information channel is not performed at the time of information transmission using an outside line, but is considered at the time of information transmission between extensions, so that it is appropriately performed between ISDN terminal devices connected to the same main wiring bus. The effect that extension communication can be performed is obtained. The transmission capacity allocated to the sub-channel depends on the IS that performs the information transmission between extensions.
Since it is made to fluctuate depending on the terminal type of the DN terminal device, there is also obtained an effect that efficient inter-extension information transmission becomes possible.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a communication system according to an embodiment of the present invention, FIG. 2 is a time chart illustrating a transmission procedure at the time of an extension call, and FIG. 3 is a data rate of 32 Kbps per terminal for an extension call. FIG. 4 is a schematic diagram showing a state of information transmission in the case of allocation, FIG. 4 is a schematic diagram showing a state of information transmission in a case where a data rate of 16 Kbps per terminal is allocated to an extension call, and FIG. It is a schematic diagram showing a situation. NT2 Private branch exchange, TE1 to TE8 ISDN terminal.

Claims (2)

(57) [Claims] In a transmission control method for a private branch exchange accommodating a plurality of ISDN terminal devices on the extension side, information transmission between the extension lines of the ISDN terminal devices accommodated on the extension line is performed by interconnecting the lines on the extension side with each other. In addition to performing the connection, the inter-extension information transmission is performed by allocating the information channel to each ISDN terminal device and allocating the sub-channel to the fixed transmission capacity during communication, while dividing the information channel. Is a transmission control method for a private branch exchange, which is not performed when transmitting information using an external line but is performed when transmitting information between extensions. 2. The transmission control method for a private branch exchange according to claim 1, wherein the transmission capacity assigned to said sub-channel is varied according to the terminal type of the ISDN terminal device for transmitting said inter-extension information.