| 摘要 |
PURPOSE: A trunk and subscriber common connection control circuit of an ISDN(Integrated Service Digital Network) BRI(Basic Rate Interface) S point is provided so as to use as a trunk connection circuit or a subscriber connection circuit, according to a selection in the ISDN BRI S point. CONSTITUTION: A control unit(1) controls a connection bus giving and taking a defined message with the system and transmits/receives call connection and an initial message with a reset. A BRI D channel control unit(2) transmits a call relevant message and control information supplied from a S point connection unit(3) to the control unit(1). The S point connection unit(3) controls the physical connection of the tip and ring of the S point. A PCM data connection unit(4) modifies 2 nos. B channels per a port of the S point connection unit(3) into the 32 channels of 2 Mbps used in the system. A priority control/PLL circuit(5) determines a port to extract a trunk clock sink to be sent to the system. A line connection part(6) is comprised of transformers(T1,T2) and switches(SW1,SW2).
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