Telephone exchange including blocking device - which prevents parallel connection of line networks to operating positions

摘要

The telephone exchange has parallel operating positions, to which outgoing and incoming transmission devices can be connected through line networks. A blocking device (ABL) prevents parallel connection of line networks to the operating positions (BPL1, BPLN). The blocking device (ABL) are connected to switching state marking circuits in the transmission devices (FUE), so that when a line network is engaged by an operating position (BPL1, BPLN) a switching-through potential is applied to it, but when other line networks in the same transmission device (FUE) are engaged by other operating positions, no switching-through potential is applied to them.