| 摘要 |
PURPOSE:To efficiently change over and use a service channel, by using each encoding and decoding circuit while it is controlled by a master station, and assigning a part of channels to a trunk, etc. in case when it has come not to be controlled by a master station. CONSTITUTION:Between a multiplexing circuit 112 and a demultiplexing circuit 113, and an encoding circuit 115 and a decoding circuit 116 are provided a gate circuit 118 and 119 for changing over a service channel to a subscriber's side or a trunk, etc. According to a service channel system which is obtained in this way, an encoding circuit 105 and a decoding circuit 106 can be connected with, for instance, any of five circuits of the circuit 112 and 113. While a channel is controlled from a master station, the circuits 105, 106 are used for a subscriber, and in case when it has come not to be controlled from the master station, for instance, channels CH 0-3 are assigned to a trunk 117, etc. and residual 4-23 CHs are assigned to subscribers. |
