To reduce a time required for connection to an opposite party by quickly detecting the end of dial input.

For example, an extension terminal TEL 1 enters an access code to use an LCR(least cost routing call) function, a special number for international calling, a country identification number, and a dial number of a called destination. The information is sent to a central processing unit 61 via a corresponding extension circuit 2-1 and a control data bus line 7. Every time one digit of the country identification number and the dial number is entered, the central processing unit 61 stores the entered number and number of digits to a storage section 62 and reads a subscriber digit number corresponding to the country identification number from the storage section 62 when the number of digits reaches three and the processing section 61 monitors whether or not the number of digits is coincident with the subscriber digit number. When the number of digits is coincident with the subscriber digit number, analysis of the number with respect to the LCR is started and, e.g. a communication network offering cheaper utility cost is selected.