Browse Prior Art Database

Automatic Trunk Release System

IP.com Disclosure Number: IPCOM000084830D
Original Publication Date: 1976-Jan-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 3 page(s) / 29K

Publishing Venue

IBM

Related People

Hernandez, P: AUTHOR

Abstract

In a PBX connected to the Gernan public network, releasing a trunk after an incoming call has been completed, can be initialized only by the calling party or by the central exchange ((CX) The latter then generates a signal wire-to-wire of a given amplitude of 50 Hz, and of at least a 80-millisecond duration.

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Automatic Trunk Release System

In a PBX connected to the Gernan public network, releasing a trunk after an incoming call has been completed, can be initialized only by the calling party or by the central exchange ((CX) The latter then generates a signal wire-to-wire of a given amplitude of 50 Hz, and of at least a 80-millisecond duration.

Such a signal can be received, on the PBX side, at any moment during the incoming call procedure. This implies a variation of the sensitivity of the signal detector according to the step being in progress. Moreover, no cycle distribution of this signal is provided by the CX; this signal is thus transmitted in realtime when the calling party hangs up or upon a logical decision made by the CX itself. The result is that the signal amplitude varies in terms of the load being applied to the 50 Hz generator at this time.

As a result, in any type of PBX installed in Germany, the trunk release signal is not always detected, which results in a permanent unavailability of the line involved, as long as a manual operation on either side has not taken place (the signal cannot be reemitted automatically on the CX side).

In order to compensate for this defect, it is proposed to simulate the release signal detection (transmitted by the CX) a given time after the called party's hanging up, or after transmission of the busy end-of-selection signal.

Two types of situations may then arise. Either the CX has transmitted the signal but the latter was not detected: the line comes back to the idle status or the CX has not yet transmitted the signal: the line is automa...