PURPOSE: To freely and simply change the channel positions and the number of effective channels by rewriting the data stored in a memory via a CPU and rearranging the channel positions of signaling signals.

CONSTITUTION: A programmable counter 15 outputs the channel number data on a 2nd group channels after receiving clocks; while a memory 13 outputs the 1st group channel numbers of a corresponding register 7 respectively. Thus the channels of the register 8 are connected to the channels of a register 8 respectively via a multiplexer 10, a signal line 12 and a demultiplexer 11. Therefore the signaling signals set at the position of a channel 26 of a digital interface of a PBX, for example, are rearranged and transmitted to the position of a channel 14 via a high-speed digital circuit. Thus it is possible to simply change the channel positions, etc., by rewriting the data on the memory 13 via a CPU.