JPH0242856A - Isdn system - Google Patents

Abstract

PURPOSE:To facilitate the development of software by adding a message for re-call control and transiting the condition of an ISDN terminal to a calling condition. CONSTITUTION:An ISDN system is provided with an exchange 20 having a call holding means 21 which temporarily holds an on-hooked call as needed at the time of on-hook in this terminal 10. Here, the exchange 20 further have a message sending means 22 to send the re-call control message through a D channel to the terminal 10, which activates this means 21, when the means 21 is activated. The terminal 10 has a condition transiting means 12 to transit its own equipment to the calling condition in correspondence to the arriving recall control message and a message sending means 13 to send a calling condition confirming message through the D channel to the exchange 20 when its own equipment is transited to the calling condition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is applied to a call processing control system for ISDN terminals. In particular, it relates to a callback method for an ISDN terminal that has gone on-hook.

〔overview〕

The present invention facilitates software development on the exchange side by keeping the terminal in a ringing state with a callback control message without executing a disconnection signal sequence in the callback procedure of an on-hook ISDN terminal. This makes it possible to easily and accurately capture the calling terminal.

[Conventional technology]

When accessing a new service or switching center, even if a terminal goes on-hook, control is performed to put the call on hold and call the terminal back again. Conventional technology for implementing this control in ISD'N terminals involves once ending the disconnection signal sequence when the terminal goes on-hook.

After that, the exchange sends a setup message to call back the terminal. The signal sequence of this conventional D channel protocol is shown in FIG. 3 for layer 3.

[Problem that the invention seeks to solve]

In this conventional callback method, once the disconnection sequence is completed, the ISD
Since N terminals are called back, the call processing program design on the exchange side is complicated. Furthermore, if the terminal is in a multipoint configuration, there is a drawback that responses from other terminals occur. Another drawback is that when editing a set-up message, a resource hunt failure (call reference hunt failure, B channel hunt failure) occurs on the exchange side, and the set-up message may not be transmitted.

SUMMARY OF THE INVENTION The present invention aims to eliminate these drawbacks and provides an ISDN system that facilitates the design of a call processing program on the exchange side during call-back processing and that can accurately capture terminals.

[Means for solving problems]

The present invention provides an ISDN system including a terminal and an exchange having a call holding means for temporarily holding an on-hook call as necessary when the terminal goes on-hook, wherein the exchange The terminal has first message sending means for sending a callback control message to the terminal that activated the holding means via the D channel, and the terminal calls its own device in response to the incoming callback control message. The present invention is characterized by comprising a state transition means for changing the state to the calling state, and a second message sending means for sending a calling state confirmation message to the exchange via the D channel when the own device changes to the calling state.

[Effect]

When an exchange that receives a disconnect message from an ISDN terminal puts the call on hold and attempts to call back the terminal, it sends a call-back control message to the terminal.

That is, the disconnection signal sequence is not performed, but instead the terminal is requested to enter the call live state by a message. The terminal that receives this callback control message transitions to the call origination state and returns an acknowledge message to the exchange.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings. 1st
The figure is a block configuration diagram showing the configuration of this embodiment.

As shown in FIG. 1, this embodiment includes a terminal 10 and an exchange 20 that accommodates the terminal 10 via a line 30. a state transition means 12 for changing the state of its own terminal in response to a callback control message (hereinafter referred to as a REALERT message) from 20; ERT ACK) message) to the exchange 20 via the line 30, and when the exchange 20 determines that a call-back is necessary when the terminal 10 goes on-hook, A call holding means 21 holds the call on-hook at the terminal 10, and a call holding means 21 holds the call on-hook at the terminal 10, and the line 30 holds the real message.
and a message sending means 22 for sending the message via the .

That is, this embodiment includes a terminal 10 and an exchange 20 having a call holding means 21 for temporarily holding an on-hook call as necessary when the terminal 10 is on-hook.
Here, the exchange 20 further includes message sending means 22 for sending a callback control message to the terminal that activated the holding means via the D channel when the holding means is activated, and The terminal 10 has a state transition means 12 that transitions its own device to a calling state in response to an incoming call-back control message, and when its own device transitions to a calling state, a calling state confirmation message to the exchange 20 via the D channel. It has a message sending means 13 for sending the message.

Next, the operation of this embodiment will be explained. FIG. 2 shows the signal sequence of the D channel protocol in accordance with the embodiment of the present invention for layer 3.
(DI 5CONNECT) When the exchange that receives the message determines that a callback is necessary, it transmits a realard message. The terminal that receives the real alert message transitions to the calling state and returns a real alert acknowledge message. When the terminal subsequently goes off-hook, a CONNECT message is sent and the terminal returns to the busy state.

The conventional call-back procedure shown in FIG. 3 requires more messages to be sent and received between the terminal and the exchange than the procedure of this embodiment shown in FIG.
When a SET-UP) message is sent, another terminal may respond as shown in FIG.

〔Effect of the invention〕

As explained above, the present invention transitions the state of the ISDN terminal to the calling state by adding a message for call-back control, so it has the effect of facilitating the software development on the exchange side compared to the conventional implementation method. be. In addition, since a disconnection signal sequence is not performed, it is possible that another terminal will respond to a callback from the exchange side, and resource hunting failures (call reference hunt failures, B channel failures) are prevented. effective.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram showing the configuration of an embodiment of the present invention. FIG. 2 is a sequence diagram showing the operation of the embodiment of the present invention. FIG. 3 is a sequence diagram showing the operation of the conventional example. DESCRIPTION OF SYMBOLS 10... Terminal, 11... Hook means, 12... State transition means, 13.22... Message sending means, 2
0...Switchboard, 21...Call holding means, 30...Line.

Claims (1)

[Claims] 1. In an ISDN system comprising a terminal and an exchange having a call holding means for temporarily holding an on-hook call as necessary when the terminal goes on-hook, When activated, a callback control message is sent to the terminal that activated this holding means.D
The terminal has a first message sending means for sending the message via the channel, and the terminal has a state transition means for changing the own device to the calling state in response to an incoming callback control message, and a state transition means for changing the own device to the calling state. The ISDN system is characterized by comprising second message sending means for sending a calling status confirmation message to the exchange via the D channel.