A telephone of the present invention is a push button type telephone whereby a DTMF signal of a first one-touch dial table is sent out in accordance with operation keys input in the general line mode and a DTMF signal of a second one-touch dial table is sent out in the private branch exchange mode. A signal sent out from a telephone in the private branch exchange mode represents a character string composed of one or more of character, starting with a character selected from a particular character group like such a less frequently used character as "A", "B", "C" or "D", for example. A function table on the part of a private branch exchange establishes ties between a character string starting with a character included in the aforementioned character group and a service function.