KR100330965B1 - Method for processing unrecovered call in integrated services digital network - Google Patents

Abstract

The present invention relates to a method for processing a recovery call of an ISDN switch that recovers a recovery call. In the present invention, a B channel can be allocated in response to a call establishment message from a predetermined terminal (T1-Tn). If not, in order to check whether the corresponding B channel is occupied by another call, inquire the call state of the called terminal T1-Tn, and as a result, the call state of the called terminal T1-Tn and the exchange. If the call is different from each other, it is determined that another call is occupied. However, if the call state of the terminals T1 -Tn and the call state of the exchange are different, it is determined that an error has occurred and the corresponding B channel is forcibly restored.

That is, the present invention has the effect that it can automatically recover by detecting the recovery call of the ISDN exchange.

Description

How to handle a non-recovery call of an integrated information network switch {METHOD FOR PROCESSING UNRECOVERED CALL IN INTEGRATED SERVICES DIGITAL NETWORK}

The present invention relates to an integrated services digital network (ISDN) exchange, and more particularly, to a method for processing a non-recovery call of an ISDN exchange for recovering a call of non-recovery.

In recent years, a comprehensive information communication network (ISDN), which digitalizes and constructs a subscriber line based on a digital telephone network, has become popular. The digital subscriber line of the ISDN subscriber logically uses a call channel (B channel) of 64 kbit / second transmission rate as two lines (2B channel) and one signal channel (D).

On the other hand, in call processing in the exchange, another call can be occupied by releasing call occupancy after the call of the subscriber is occupied, that is, after the call state ends. However, even when the call occupancy is released due to an error on the user network interface, a call between the subscriber and the switch may be continuously occupied, that is, a recovery state may occur. In this non-recovery state, the service of the new call is impossible, and it is necessary to recover it forcibly, but there is no method for automatically detecting and recovering such a state.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide a method for processing a recovery call of an ISDN switch which detects and recovers a call in a recovery state.

In order to achieve the above object, the present invention provides a method for monitoring and restoring a B channel recovery state between an exchange and a terminal of an integrated information communication network, and if a call setup request message is provided from the terminal, whether the B channel can be allocated to the terminal. Judging; Determining whether another call exists in the terminal if the B channel allocation is impossible for the terminal, and inquiring a call state of the terminal if the other call exists; If the call state of the terminal in response to the call state query is different from the call state of the exchange, then restoring a B-channel of the corresponding terminal.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic block diagram of a comprehensive information communication network for carrying out a method for processing a call recovery process according to the present invention;

2 is a flowchart illustrating a method for processing a non-recovery call of an integrated information network switch according to the present invention.

<Description of the symbols for the main parts of the drawings>

T1-Tn: Terminal 10: Switchboard

11 processor 12 subscriber registration exchange subsystem

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

1 is a schematic block diagram of an ISDN exchange performing a method for processing a recovery call of an ISDN exchange according to the present invention. As illustrated, a plurality of ISDN terminals T1 -Tn are connected to the exchange 10 of the present invention. . The switch 10 includes an Access Switching Subsystem for Subscriber (ASS) 12 for converging calls of terminals T 1 -T n, and a processor for controlling the ASS 12. (11) is comprised.

Calls collected in the ASS 12 are switched through a switch in the exchange 10 to be connected to the terminating terminals T1-Tn.

In the switch 10 having such a configuration, calls from the terminals T1-Tn are condensed at the ASS 12 as described above, and occupy an information path, i.e., a channel B, with the destination terminals T1-Tn. Here, the call recovery state means that the information path continues to be formed even though the information path of the B channel formed between the terminals T1 -Tn and the switch 10 should be blocked.

The processor 11 communicates with the above-mentioned terminals T1 -Tn in the D channel and selectively controls the path formation of the B channel.

2 shows a procedure in which the processor 12 detects and recovers a call in an unrecovered state in an exchange having the above-described configuration.

It is practically impossible because the processor 11 always monitors whether there is a recovery call and automatically recovers for the recovery call. Therefore, as will be described later, in the present invention, when a call origination message, i.e., a call setup message, is provided from the terminal T1-Tn, the state of the channel B for the terminal T1-Tn is monitored, and the channel B is in use, that is, no fire. If it is in a recovery state, restore it selectively This will be described in detail below.

When a call setup message is provided from the predetermined terminals T1 -Tn (101), the processor 11 detects (102) the B channel state with the calling terminal (T1-Tn). That is, it is determined whether both B channels between the calling terminals T1 -Tn are in use, and if one of these B channels is not in use, that is, the call is not occupied, the process proceeds to step 103 where normal outgoing call processing is performed. To set the call to the predetermined destination terminal (T1-Tn) requested by the calling terminal (T1-Tn).

However, as a result of the determination of step 102, if both B-channels are in use, i.e. in a call state, the processor 11 proceeds to step 104 where another call is already present in the calling terminal T1-Tn. Determine authorization. That is, the processor 11 determines whether the terminal T1-Tn which has sent the call setup message is in a state of performing another terminal T1-Tn call. As a result of the determination of step 104, the processor 11 proceeds to step 107 if another call already exists, or to step 105 if no other call exists.

In step 105, the processor 11 determines whether processing for a call in progress is being performed even if no other call exists. That is, until one call is set up and released, a call setup step, a call setup response step, a call step, and a call release step must be performed, and the call is not released until the call release step is performed instead of the call step. Keep it. Therefore, the processor 11 determines whether the processor 11 is in the process of processing the call when the call exists as a result of the determination in step 104.

As a result of the determination in step 105, if the call is not being processed, the processor 11 may be mistaken as a call exists even though the call does not exist in the corresponding B channel. Proceed to) and perform the procedure of forcibly restoring the corresponding B channel in the network.

On the other hand, if the determination result of the steps 104 and 105 indicates that the call exists or is in the process of processing the call, the processor 11 proceeds to step 107 to send a call setup message to the calling terminal T1-Tn. Notifying that the corresponding call setup has failed, and transmits a call status query signal to the corresponding calling terminal (T1-Tn) (108). After transmitting the call status query signal, the processor 11 drives an internal timer. The reason for driving the timer in this way is as follows.

The caller terminal T1-Tn receives a call state inquiry signal and responds to it as a response to the call state, ie, call state, call establishment answer state, call state, or call release state. Send a signal to the processor (11). However, there may be a case in which the call terminal query signal is not received by the calling terminal T1-Tn due to an abnormality in the transmission path or the call status response signal may not be transmitted due to an abnormal light of the calling terminal T1-Tn. . In this case, the call does not need to be maintained continuously. Therefore, the processor 11 proceeds to step 115 if the call status response signal is not provided from the corresponding calling terminal T1-Tn within a predetermined time after the timer is driven by step 109 (111). Performs a procedure to forcibly recover the corresponding B channel.

On the other hand, if the call status response signal is provided from the calling terminal T1-Tn within a predetermined time by the timer as a result of performing steps 110 and 111, the processor 11 proceeds to step 112 to call this call. Receive the status response signal and reset the timer. The processor 11 determines whether the call state of the terminals T1 -Tn and the call state of the switch 10 coincide with each other (113). As a result of the determination of step 113, the call state of the corresponding terminals T1-Tn and the call state of the switch 10 coincide with each other, which means that the corresponding B channel is in a normal state in use by a normal call. 11) end all processes.

However, if the call state of the terminal T1-Tn and the call state of the switch 10 do not coincide with each other as a result of the determination of step 113, the processor 11 proceeds to step 114 and the terminal T1- It is determined whether Tn) is performing a call release procedure. That is, if the originating terminal (T1-Tn) is performing the call release procedure, it would be desirable for the exchange 10 to perform the call release procedure without having to go through the recovery process separately. Thus, processor 11 proceeds to step 116 to perform a normal call release procedure. However, if the call processing state of the calling terminal T1-Tn and the exchange is different as a result of the determination of step 113, the call processing state of the calling terminal T1-Tn or the exchange 10 is an abnormal state, which eventually Since the allocation of the B channel to the corresponding calling terminal T1 -Tn is in an incorrect state, the processor 11 proceeds to step 115 to perform a forced recovery procedure for the allocated B channel.

As described above, in the present invention, if the corresponding B channel cannot be allocated when a call is requested from the subscriber, the B channel is occupied by another call or an error state due to a mismatch of call processing states between the exchange and the corresponding calling terminal. By determining the acknowledgment, when the error state, the B channel is forcibly restored, thereby effectively recovering the non-recovery state due to the error.

Claims (4)

A method for monitoring and recovering a B channel recovery status between an exchange and a terminal of a general information communication network, Determining whether B channel allocation is possible to the terminal when a call establishment request message from the terminal is provided; Determining whether another call exists in the terminal if the B channel allocation is impossible for the terminal, and inquiring a call state of the terminal when the other call exists; And restoring a B-channel of the terminal if the call state of the terminal in response to the call state query is different from the call state of the exchange. The method of claim 1, And notifying the calling terminal that call setup is impossible if the B-channel allocation for the terminal is impossible. The method according to claim 1 or 2, And restoring a corresponding B channel on the network side if call state information is not provided within a predetermined time from the terminal in response to the call state query. The method of claim 1, Determining whether the call state of the terminal is in a call release procedure state when the call state of the terminal in response to the call state query is different from the call state of the exchange; Performing a normal call release procedure if the call state of the terminal is a call release procedure; And forcibly recovering the corresponding B channel on the network side if the call state of the terminal is not in a call release procedure state.