Abstract: A digital multiplexer for transmitting control, signaling and speech information in digital form between a central telecommunications office (CO) and a plurality of remote terminals. The system serves a plurality of lines at the exchange and couples those lines to subscriber stations associated with those lines through a digital span line such as the generally known Tl line between a CO terminal and the remote terminals. A maximum of 32 channels are provided using continuously variable slope delta modulation, with the modulation and demodulation being performed in line circuits individual to each line being served. A time division concentration stage enables the system to service 128 lines over the 32 channels with each channel having a memory position for storage of line address information.