PURPOSE: To ensure the communication when a master equipment exists at an optional location where a telephone set is carried in a premises by providing a means connectable to the master equipment except a specific master equipment under a special condition.
CONSTITUTION: A call identification signal (ID signal) of an optional telephone set is stored in an ID memory collation section 1-1, which is fitted to the output side of a reception section 1-2 of the master equipment 1. When a telephone set 2 making a call is a telephone set (B) 2 not belonging to the master equipment 1, the ID information of the telephone set (B) 2 is stored in the ID memory collation section 1-1, then the ID memory collation section 1-1 sends a signal of call OK to a control section l-3 to attain the talking from the telephone set (B) 2. When a call comes to the master equipment 1, the ID information of a telephone set (A) 2 belonging to the master equipment l is called at first, and when no reply comes from the telephone set (A) 2, an incoming signal is sent sequentially to all the telephone sets 2 corresponding to the ID information stored in a memory circuit in the ID memory collation section 1-1 at each prescribed interval and the telephone set (P)2 receives surely the call in the vicinity of the master equipment 1 being the destination.
TAKITA HAJIME
IWAZAWA OSAMU
ARIIZUMI YOSHIO
KOKUSAI ELECTRIC CO LTD