In a CTI system, when a wireless terminal is called in response to a transmission request from a personal computer, a key telephone main unit adds to a call signal identification information indicating that a call is based on the transmission request from the personal computer. When the call is received, the wireless terminal judges whether or not the identification information is added to the call signal. When it is judged that the identification information is added, the wireless terminal automatically answers the call. Otherwise, the wireless terminal does not automatically answer. Thus, in case of transmission from a CTI application, operability and convenience are improved.