| 摘要 |
PURPOSE:To improve the using efficiency of a relay line by detecting a specific pattern signal in an incoming exchange connected to an outgoing exchange through a digital relay line so as to discriminate a data signal. CONSTITUTION:The incoming exchange 2 is provided with a specific pattern detecting circuit on a trunk DTK2. when the incoming trunk DTK2 receives data of all zero, the output of a gate G goes to '1' level. With the aid of the output level '1' of the gate G an incoming common controller CC2 recognizes the reception of data of all zero, and at the time of incoming to a DTEC connects directly it to a DLC2, while at he time of incoming to a DTED the controller CC2 connects it to an LC2 through a MDP1. Namely, since the incoming exchange 2 can discriminate whether or not the call is of a digital data signal, it can decides whether it has to use a MODEM pool MDPL or MDP2 in order to connect an incoming terminal device DTE. Thus a data call can be connected without classifying digital relay lines into a group, and therefore the using efficiency of the digital relay line can be remarkably improved.
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