JP2878375B2 - Call link control method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication link control method for a telephone switching network connected by a common channel signaling method.

[Conventional technology]

Conventionally, when a telephone exchange is connected using a common channel signaling method,
For example, in a connection between two telephone exchanges that connect the telephone exchange a and the telephone exchange b, if two subscriber terminals in the telephone exchange a start a call via the telephone exchange b, the telephone exchange b side And recognizes that the call is a tandem call on the same route, and requests the telephone exchange a to change the connection of the telephone link by a common line signal.
The side connects to each other in its own office, releases the telephone link between telephone exchange a and telephone exchange b, and makes effective use of the telephone link.

 Hereinafter, a conventional control method will be described with reference to the drawings.

FIG. 11 shows telephone exchange a (PBXa) and telephone exchange b (PB
Xb) using a common channel signaling system.
Each of the PBXa and PBXb houses an extension terminal. Here, for example, during the extension terminal b of the extension terminal a ₁ and PBXb of PBXa the call, performing a transfer operation to the extension terminal a ₂ to extension terminal b is accommodated in PBXa, FIG. 12 (1)
As shown in (2), a call state is established using two call links between PBXa and PBXb. At this time, since the tandem connection of the same route in PBXb, against PBXb is PBXa, call link connection by pre Ji because a defined signal format for connecting the extension terminal a ₁ and the extension terminal a ₂ A change request signal is notified via a signal link (common line). On the other hand, in the PBXa side thereof receives a call link connection exchange request signal, performs a connection extension terminal a ₁ and the extension terminal a ₂ in the local station, further, PBXa and PBXb between calls linked 2 that was used in Execute the book release process, the twelfth
The state shown in FIG.

Next, telephone exchange a (PBXa) and telephone exchange b (PBX
b) and conventional operation in a delta (Δ) type network in which telephone exchange c (PBXc) is interconnected.

For example, when a call is made between the extension terminal b accommodated by PBXb and the extension terminal c accommodated by PBXc via the PBXa, the connection cannot be switched to the call link between PBXb and PBXc.

Hereinafter, a control method in a conventional delta network will be described.

FIG. 13 is a diagram in which each of PBXa, PBXb, and PBXc is interconnected by a common channel signal system to form a delta-type network, and each telephone exchange houses an extension terminal. ing. Here, for example, as shown in FIG. 14 (a), while the extension terminal b of PBXb and the extension terminal a of PBXa are in a call, the extension operation of the extension terminal a of PBXa performs the transfer operation to the extension terminal c of PBXc. When done, via PBXa as shown in Fig. 14 (b)
A call link between the extension terminal b of PBXb and the extension terminal c of PBXc was formed.

[Problems to be solved by the invention]

In the above prior art, in a telephone exchange network constituted by a delta type network, even if an outgoing telephone exchange and an incoming telephone exchange are connected via a suspended telephone exchange, the outgoing telephone exchange and the incoming telephone exchange are directly connected. The connection could not be changed to be connected.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a telephone exchange network constituted by a delta network, in which a call link between an extension terminal of an originating telephone exchange and an extension terminal of an incoming telephone exchange is formed via a suspended telephone exchange. In such a case, the call link is switched, and a call link is directly set between the calling telephone exchange and the called telephone exchange so that the call link can be used efficiently.

[Means for solving the problem]

According to the present invention, in a telephone exchange network configured as a delta type, when performing a call connection process, the exchange determines whether or not a tandem connection is established, and if the tandem connection is established, the exchange switches to a preceding exchange. Information indicating that the connection is a tandem connection is transmitted, and the preceding exchange reconnects the call using a communication link that does not become a tandem connection based on the received information.

[Action]

The telephone exchange that has been connected in tandem at the time of the call link connection notifies the originating telephone exchange of the connection partner (incoming) telephone exchange by a common line signal. On the other hand, the calling telephone receiving this notification newly captures the call link corresponding to the called telephone exchange, adds a call link connection change request in the address signal at the time of activation, and transmits a common line signal to the called telephone exchange. Send out. Upon receiving the address signal, the terminating telephone exchange executes a connection change process and returns a response signal. As a result, the new call link becomes valid, and the call link that was previously in use is released.

〔Example〕

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

FIG. 1 is a configuration diagram of a telephone exchange network according to the present invention.

In the figure, each telephone exchange (PBXa, PBXb and PBXc) has a central control unit (C
P), a storage device (MM) for storing various programs such as an exchange operation control program, station data, various tables, etc., and a common line for transmitting and receiving data (information) different from call signals such as control data for call setting. Signaling equipment (CSE), time division switch (SW), extension terminal (TEL), and extension terminal (TE
L) and a subscriber circuit (LIN) that interfaces with the time division switch (SW). As shown in the figure, the telephone exchanges are connected to a call link via a trunk (TRK), and are further connected to a signal link (common line) different from the call via a common line signaling device (CSE). )It is connected.

FIG. 2 is a diagram for explaining the operation of call link connection control in the network of FIG.

First, Fig. 2 (1) shows that TELb housed by PBXb
FIG. 3 is a diagram showing a state in which a telephone call is made to TELa contained in PBXa and a telephone call is being made.

FIG. 2 (2) shows that, from the state of FIG. 2 (1), TELb accommodated by PBXa transfers PBXc during a telephone call.
FIG. 7 is a diagram showing a state in which TELc that is accommodated is called. At this time, the call from TELb is on hold at PBXa.

FIG. 2 (3) shows a state in which TELa ends the call and completes the transfer operation in the state of FIG. 2 (2), and a call between TELb and TELc is performed through the route of PBXb-PBXa-PBXc. Status,
That is, the call link between PBXb and PBXa, and PBXa and PBXc
It is a figure showing the state where a call is set up using a call link between them. Note that this state is referred to as a "tandem connection" of the call link.

As described above, when the call link becomes a tandem connection, the tandem-connected PBX, that is, PBXa, transmits a call link status notification signal (1a) for notifying the status of the call link to the PBX, ie, PBXb. Send via link. The call link state notification signal (1a) includes information for notifying the PBX of the connection destination, that is, PBXc.

FIG. 2 (4) shows that the PBXb that has received the call link status notification signal (1a) is connected to the connection destination PB included in the signal.
Based on the information of X, it recognizes that it is connected to PBXc,
This shows a state in which the communication link 2 connected to the terminal c is newly acquired, and the connection change request signal (1b) is transmitted via the signal link. Note that the connection change request signal (1b) includes, as additional information, call link information that is a target of call link connection change.

FIG. 2 (5) shows that the PBXc identifies a call link for which a call link connection change request is to be made, based on additional information in a connection change request signal (1b) of a newly generated call.
FIG. 13 is a diagram showing a state in which a connection is newly made with Lc and a response signal (1c) indicating that the connection change has been completed is returned to PBXb via the signal link. In PBXb, the response signal (1
When c) is received, call link 2 and TELb are connected, and PBXb
And release the call link used between PBXa and
The call link used between PBXa and PBXc will also be released.

Fig. 2 (6) shows that the telephone call between TELb and TELc is PBXb and PBXc.
FIG. 3 is a diagram showing a state established using the communication link 2 between them, that is, a diagram showing a state at the end of the operation of the communication link connection control.

FIG. 3 is a diagram showing a configuration of a call control level 4 signal defined by the CCITT recommendation No. 7 common channel signaling system.

In FIG. 3, a label is an area of information indicating a call to be controlled in transmission and reception of a signal, and the label of the signal is determined by a station number assigned to each telephone exchange in a network connected by a common channel signaling method. A line number assigned to each call link that is predetermined between the telephone exchanges, including a source station number indicating a source telephone exchange and a destination station number indicating a destination telephone exchange of a signal to be transmitted. It is composed of The heading code is an area indicating the type of a signal to be transmitted. Furthermore, the additional information area is provided when various types of signals require additional information, and various additional information can be obtained by making a decision in advance during each telephone exchange period. Is an area in which it is possible to transmit and receive

FIG. 4 shows the call link state notification signal (1a) shown in FIG. 2 (3), the connection change request signal (1b) shown in FIG. 2 (4), and FIG. 2 (5). FIG. 9 is a diagram illustrating a signal configuration of a response signal (1c) (a configuration example of a common line signal).

The call link status notification signal (1a) includes a label, a heading code indicating that the call link status notification signal is provided,
It is composed of a connection destination station number indicating the telephone exchange (PBX) of the connection destination and a connection destination line number indicating the communication link of the connection destination.

The connection change request signal (1b) includes a label, a heading code indicating that the signal is a connection change request signal, and a connection change line number indicating a communication link for which connection change is requested.

The response signal (1c) is composed of a label and a heading code indicating the response signal. Note that the response signal (1c) may use a response signal (ANN signal) defined by the CCITT recommendation No. 7 common channel signaling method.

The connection change request signal (1b) can also use an address signal with additional information (IAI signal) by adding some information.

FIG. 5 is a diagram showing a sequence of information transmitted and received between signal links (common line signals) when the operation of the communication link connection control shown in FIG. 2 is performed.

When a call is being made between PBXb and PBXc,
When a tandem connection of the call link is made on PBXa, PB
Xa sends a call link status notification signal (1a) to PBXb. When receiving the call link status notification signal (1a), PBXb captures a new call link directly connected to PBXc, and transmits a connection change request signal (1b) to PBXc. The PBXc receives the connection change request signal (1b), recognizes that a new call link has been activated, and determines that the connection change request signal (1b) is valid. Signal) to the PBXb, and performs a call link connection change process. When the call link connection changing process is completed, a response signal (1c) is transmitted to PBXb. On the other hand, PBXb sends a connection change request signal (1b) to PBXc, and then receives a response signal (1c) from PBXc, thereby recognizing that the new call link has become effective and recognizing the call link within PBXb. In addition to performing connection change processing, processing for releasing the communication link used first is performed. This call link release processing is for transmitting a signal (CLF signal) for releasing the call link to the PBXa. When the CLF signal is transmitted to the PBXa in this way, the communication links between the PBXb and the PBXa and between the PBXa and the PBXc are released by the procedure shown in the figure. The ACM signal (startup completion signal), CLF signal (disconnection signal), and RLG signal (restoration completion signal) used in FIG. 5 are recommended by CCITT. This signal is specified by the No. 7 common channel signal system.

FIGS. 6, 7, and 8 are flow charts for explaining the processing of the telephone exchange which performs the communication link connection control.

FIG. 6 is a flowchart showing a process performed after the connection of the call link is completed.

In FIG. 6, when the communication link connection processing is executed, first, it is checked whether or not this communication link is in tandem connection (601 in FIG. 6), and whether or not the communication link is in tandem connection is identified. (FIG. 6, 602). If the connection is not dandem, no processing is performed. Also, in the case of a dandem connection, the line number of the call link and the call link of the dandem connection to the destination telephone exchange, that is, the incoming call link, The station number of the telephone exchange to which the call link is connected is edited in the call link status notification signal (1a), and processing for transmitting the signal is performed (FIG. 6, 603).

FIG. 7 is a flowchart showing a process when the communication link state notification signal (1a) is received.

In FIG. 7, when the communication link status notification signal (1a) is received, first, the received communication link status notification signal (1a) is received.
The connection destination station number is extracted from a) (FIG. 7, 701). Next, based on the extracted connection destination station number, it is checked whether or not a communication link directly connected to the connection destination station exists in the own station, and if so, the communication link is captured (No. 7). (Fig. 702). At this time, it is determined whether or not the call link can capture the call link due to, for example, all calls (No. 7).
(FIG. 703) If the call cannot be captured, the received call link state notification signal (1a) is ignored and the connection change is abandoned.
If the call link can be captured, the connection line number included in the call link status notification signal (1a) is set as the connection change request signal (1b) as a start signal of the call link, and a new setting is made. The connection change request signal (1b) is transmitted to the other station of the call link (FIG. 7, 704). Next, the system waits for a response signal corresponding to the connection change request signal (1b), and upon receiving the activation completion signal and the response signal (1c), connects the newly captured call link to the target terminal (FIG. 7). , 705) and release processing of the previously connected communication link is performed (FIG. 7, 706).

After the connection change request signal (1b) is transmitted, if an activation incomplete signal is received or a reply signal does not arrive within a predetermined time, the current state is maintained and the connection change processing is not performed.

FIG. 8 is a flowchart showing a process when the connection change request signal (1b) is received.

In FIG. 8, when the connection change request signal (1b) is received, the received connection change request signal (1b) is handled in the same manner as a normal call setting signal. That is, first, the connection change request signal (1b) is included in the connection change request signal (1b). The connection line number included is extracted (801 in FIG. 8), the connection line to be connected is determined based on the extracted connection line number, and the activated call link is connected to the extension terminal. Change the connection. (FIG. 8, 802).
Next, after performing the operation of switching the connection of the call link in the step of 802, it is determined whether or not the processing of the connection change has been performed normally (803 in FIG. 8, 803). If done (if signal reception is acceptable),
A start completion signal and a response signal (1c) are returned to the start station.
If the connection change processing has not been performed normally (if signal reception is unacceptable), a start incompletion signal is returned to the start station.

That is, as a result of performing the above operation, if the connection change request signal (1b) is permitted, the new call link activated and the connection change line number included in the connection change request signal (1b) are indicated. During the connection of the call link to be connected, a process is performed to connect the other party, and when the connection change is completed, a response signal (1c) is transmitted to the newly activated call link.

In the above, one embodiment of the present invention has been described with reference to the diagrams shown in FIGS. 2 (1) to (6) in the network configuration shown in FIG. 1, but the common line signal 1 shown in FIG.
Using a, 1b, and 1c, it is possible to cope with the control of the call link even in a network having another configuration.

For example, in the network configuration shown in FIG. 1, the connection change processing shown in FIGS. 9 (1) and (2) can be controlled by transmitting and receiving the call link state notification signal (1a).

Hereinafter, the call link control when the tandem connection as shown in FIG. 9 (a) is established in the network configuration shown in FIG. 1 will be described with reference to the flowchart shown in FIG.

First, when PBXb recognizes that it is a tandem connection,
A call link status notification signal (1a) indicating a connection change request is transmitted to PBXa. On the other hand, when the PBXa receives the call link status notification signal (1a), it extracts the connection destination station number included in the received signal (1a) (FIG. 10, 1001), and extracts the extracted connection destination station number. Is compared with the own station number to determine whether they are the same (FIG. 10, 1002). As a result of the determination, if the number is that of another station, the above-described processing is performed according to the flowchart shown in FIG. If the number is the same as that of the own station, it is recognized that the connection is between the extension terminals in the own station, and the connection processing between the target extension terminals is performed (FIG. 10,
1003) The call link used between PBXa and PBXb is released (FIG. 10, 1004).

Thereby, in the network configuration shown in FIG. 1, it is possible to change the connection of the return type tandem call as shown in FIG. 9 (a) as shown in FIG. 9 (b).

〔The invention's effect〕

According to the present invention, an unnecessary call link can be switched to an empty state in a telephone switching network connected by a common channel signaling method, so that the call link can be used efficiently.

In addition, this can reduce the number of connection steps in a call within the network and improve the call quality.

Furthermore, it is possible to reduce the blocks that occur for the call link.

[Brief description of the drawings]

FIG. 1 is a diagram showing a network configuration of the present invention, FIGS. 2 (1) to (6) are state transition diagrams for explaining the operation of the present invention, FIG. 3 is a diagram showing a basic configuration of common line signals, FIG. 4 is a diagram showing a configuration example of a common line signal used in the present invention, FIG. 5 is a diagram showing a transmission / reception sequence of the common line signal, and FIGS. FIGS. 9 (a) and 9 (b) are flow charts showing the control, and FIGS. 9 (a) and 9 (b) are diagrams for explaining the operation of another embodiment of the present invention. FIGS.
(2), FIG. 13, and FIGS. 14 (a) and (b) are diagrams for explaining the conventional technique. 1a: Call link state notification signal, 1b: Connection change request signal, 1c: Response signal to connection change request signal.

Claims (1)

(57) [Claims] 1. A telephone exchange network in which a first exchange, a second exchange, and a third exchange are connected in a delta configuration, wherein the first exchange includes a telephone set accommodated in the first exchange. And the telephone connection state between the telephone housed by the second exchange and the telephone connection state between the telephone housed by the second exchange and the telephone housed by the third exchange. A recognizing means for recognizing that the second exchange and the third exchange are in a tandem connection state via one exchange, and recognizing that the second exchange and the third exchange are in a tandem connection state by the recognizing means; Means for transmitting a call link status signal including station information indicating the third switch and line information to be reconnected to the switch, wherein the second switch is connected to the switch from the first switch. Receiving the link state signal, the mobile station captures a new communication link directly connected to the third exchange recognized by the station information included in the communication link state signal, and then switches the connection to the third exchange. Means for transmitting a connection change request signal including the target line information; and receiving a response signal to the connection change request signal from the third exchange, the third exchange accommodating through the first exchange. Means for reconnecting a telephone in a call connection state with the telephone to the new call link, and for making a request to release a call link set for the first exchange, the third exchange Upon receiving the connection change request signal from the second exchange, based on the line information of the connection change target included in the connection change request signal, via the first exchange, Second
After switching the telephone which is in a call connection state with the telephone accommodated by the exchange to the new call link,
A communication link control system, comprising: means for transmitting the response signal to the exchange of (1).