Telephone subscriber connection - uses cross point routing to other circuits where subscribers are monitored on successive basis

摘要

In telephone installations where the loop state of subscribers is monitored on a successive basis, the process can involve memorisation of the subscriber state and at least, several relays. This system concerns an installation of the type where each subscriber is connected via coupling stages to a group of connection units. The group has routing finders that identify the loop state of the subscriber instrument. Evaluators recognise the diminution of loop current or the open condition when the hand set is in place. The coupling stages can be Triac cross-points and may be controlled by diodes.