Telephone private branch exchange with conference facility - has amplifiers inserted between corresponding column lines of different coupling matrices

摘要

The telephone branch exchange uses coupling fields (KF1,KF2) and centralised and decentralised control devices. The column lines of at least 2 coupling fields (KF1,KF2) are coupled via respective amplifiers (V1,Vn, VA1) allowing a call received via one coupling field line to be transferred to the second coupling field (KF2). Pref. each coupling field (KF1,KF2) is coupled to a termination device TSK, TSG) which allows a speech memory to be inserted in the connection path when a time delayed information transfer is required.