Procedure for the exchange of control signals, By means of employing a system in traffic link in telephone networks, particularly in networks supple- tories apparatus with automatic transmission in sub-installations

摘要

The method comprises the transmission of main and secondary signals, the address (NK2 to NKn) of the called-back telephone station being essentially transmitted to the main system when a connection is set up between a main system (HA) and a dial-up sub-system (UA) and when a call-back is initiated in the dial-up sub-system, and being stored in a special memory in the main system. 50-Hz AC signals and audio-frequency signals in particular are used as pulse signals. IMAGE