Telephone exchange call-back connection circuit - has counting chains in branch exchange translations connecting call-back requests as required

摘要

The circuit is for step-by-step selector systems in main and branch exchanges, with subscriber circuits connectable by selector stages to branch exchange translations. The subscriber circuits can be connected through tie-lines to main exchange translations, whose dialling translations, which can be connected by further selector stages to the main exchanges translations, make a connection to a main subscriber line in case of through traffic, and to another extension in case of a call-back. Call-back circuits (RF1-RFN) are allocated to the branch exchange translations (UUE). When free, they can be connected by a common control unit (RFG) to the branch exchange translations (UUE). These call-back circuits have in addition to a pulse responder a counting chain which controls the dialling pulses from the branch exchange translations (UUE), so that in case of a call-back to extensions (TA1-TA2) in a branch exchange (UA), a call-back extensions circuit (RTS) directly allocated to the branch exchange translation is connected. In case of call-backs to subscribers (TA) in the main exchange (HA) the extension line (NAL) is connected.