PURPOSE: To improve the service of call connection by calling sequentially automatically plural called parties registered in advance through the dialing of a special number by a caller.

CONSTITUTION: A call tone is transmitted to an extension subscriber 1 via an outgoing register trunk 5 and a channel circuit network 10, a special number for call tone information registration is dialed and an address of a called party information storage memory 120 in a main storage device 12 is designated. After the registration of a required extension number is finished, when the extension subscriber 1 hooks off and dials a special number for automatic call, a CPU11 reads an address in the memory 120 from the device 12 based on special number receiving information from a trunk 5 and called to the extension subscriber 2. When the subscriber 2 responds to it, talking with the subscriber 1 is attained via a bus. When the subscriber 2 hooks on at the end of call, the CPU11 calls an extension subscriber 3 similarly. Thus, plural called parties are called automatically and sequentially.