Local communication system among ISDN terminal equipments

摘要

A local communication system among ISDN terminal equipment in a user's premises are connected to a local passive bus of the LSDN basic-access interface. The present system can establish the local communication through a network termination unit among ISDN termination equipment. In order to establish such a local communication, a multiframing scheme is taken on a passive bus forming multiframes by combining together the predetermined number of frames which are as defined in the I.400 series of CCITT recommendations. The network termination unit has a switching device for coupling two circuit-switched type communication channels (B1, B2) on the passive bus in one direction of transmission with the two other channels (B2, B1) in the other direction to establish local communication. Alternatively, the switching device couples the two channels on the passive bus with those on the subscribed line to establish external communication. Each of the terminal equipments has a device for requesting the local communication when required.