TIME DIVISION MULTIPLEX

PROBLEM TO BE SOLVED: To multiplex efficiently mixed signals of a plurality of a data signal, a signaling signal and a status signal at different transmission speeds within a frequency band of 8kb/s×m. SOLUTION: A multi-frame MF of m-bit×40-frames is formed in a time slot of 64kb/s, remaining frames except optional one frame are divided into groups G1-G13 each consisting of 3 frames and of (m×3) bits, one bit in the m×3 bits is used for a frame synchronization bit F and the other bits are used for information transmission bits, a set of (m×3-1) of the information transmission bits with a same number is formed in the multi-frame, each frame is synchronous by using the frame synchronization bit F in terms of the multi- frame MF and a channel is formed by a set of the information transmission bits whose number corresponds to the transmission speed of the channel.