PURPOSE: To eliminate need for any special operation such as off-hook of a key telephone set to release the setting of repetitive automatic recalling by releasing the setting of automatic recalling in case of the presence of a replay from an opposite station as the result of automatic recalling, generating an external line incoming tone and informing the reply of opposite station to a caller.

CONSTITUTION: If not a busy tone but a call tone comes from an opposite station, a call tone detection circuit 21g of a trunk line interface section 2 of a trunk line Lg (not shown) being a calling trunk line at that time detects a received call tone and outputs the received call tone detection data to a control circuit 51. Then the control circuit 51 releases the setting of repetitive automatic recalling and controls an external line incoming sound source 31 of a channel switch section 3 to a key telephone set Ti having an extension number stored in a storage circuit 53 to send an external line incoming tone. As a result, an external line incoming tone is rung from the key telephone set Ti to inform the replay of an opposite station to the caller. Thus, no special operation such as hook-off of a handset of a key telephone set is not required to release the setting of the repetitive automatic recalling.