PURPOSE: To prevent the occurrence of malfunction by providing with a detection means for off-hook and an idle state.

CONSTITUTION: When an incoming call is received, a control section 5 applies ACD(automatic call distribution) processing to the call when a connection enabling extension terminal equipment 7 is in existence to connect the call to a terminal equipment 7 in a group corresponding to the incoming call. When no connection enabling terminal equipment is in existence, the control section 5 registers the incoming call in a queue table 4a of a memory 4. When no incoming call arrives, the control section 5 connects a head incoming call in the queue to the terminal equipment 7 wihout being hooked off while ACWT is being activated. If there is no incoming call in the gueue, in the case that the terminal equipment 7 is not hooked off, registration is made in the queue table or head call is reached to the terminal equipment and the control section 5 transfers to other processing. When the ACWT is being activated and an idle terminal equipment is hooked off, the ACWT is cancelled and the head incoming call is connected. The operator has to make only hook-off operation, handling time is saved and the occurrence of malfunction is prevented.