Control means of an exchange comprising connection means for accommodating a telephone and the control means for controlling the accommodated telephone, receives a dial signal from the telephone without causing the telephone to respond to an incoming call when the telephone that is performing incoming call ringing is hooked off, causes the hooked-off telephone to respond to the incoming call when the received dial signal is a first dial signal, and causes the telephone as a call source to make a call without causing the hooked-off telephone to respond to the incoming call when the received dial signal is a second dial signal. Thereby, it is possible to make a call even during incoming call ringing.