The connection between a terminal and an analog switch convenience analog

摘要

The system connected to an analog telephone terminal (ta) and an analog telephone exchange (cm) through a telephone subscriber line (1n) supporting two data channels b and a signaling channel d, provided at its ends of the first and second equipments. In the direction changeover switch to terminal, the second device (ec) converts the speech signals and of tone transmitted by the switch in digital form in a dedicated channel b, and generates signaling messages telephone in the d channel, for example, in response to ringing pulses clocked, pulses of the pin and the polarity inversions. The first equipment (ea) converts the analog digital signals of the dedicated channel and transmits the telephone signallings to the terminal. In the other direction, the signalling messages are generated and converted into the two pieces of equipment. The second channel b can convey signals to another terminal.