PURPOSE: To provide the service in response to the priority of a caller or the like by executing the service based on an incoming call processing index in response to the caller information to the caller when an incoming call comes from an external telephone set to a called telephone set in an exchange.

CONSTITUTION: When an incoming call from a trunk 17 comes to an exchange 11A and caller identification information is in existence in received numeral information, a caller information recognition section 13-3 stores caller ID information to a data section 14-3. An analysis section 13-1 analyzes called party dial information received from the trunk 17 to decide the called extension. The recognition section 13-3 extracts the caller ID information from the data section 14-3 when the identification of the caller is attained based on the information of the caller from the data section 14-3. When the information relating to the caller stored in the data section 14-3 has urgent and priority significance, the call is received with priority over other incoming call. When a transfer destination telephone number is included in the ID information, a transfer destination registration number is extracted and the call from the trunk 17 is transfer red to the transfer destination telephone number under the control of a conducting section 13-7.