To provide a private switchboard for easily realizing data communication using a plurality of B channels even at the time of terminating call by a key number function.

In a private switchboard 1, when call setting processing is executed by a CPU 4, an incoming call is transmitted to a prescribed terminal by the pilot function, and when the caller placing the call is registered in advance in a caller's number registration table, communication with the caller is operated by a B channel pair ring being communication using a plurality of sets of B channels.