PURPOSE: To prevent malfunction of a dialer main body by adopting a two-way interface between a CPU and the dialer main body.

CONSTITUTION: A CPU 3 connects to a dialer main body 2 through a two-way interface 4 and decodes data sent from the dialer main body 2, and when the code is a code defined as a dial code, a dial command corresponding to the key is sent to the dialer main body 2 and when the code is a code of user definition key 12, the processing in response to the defined content is executed. Since the CPU 3 and the dialer main body 2 are connected by the two-way interface 4, the CPU 3 reads the state of the dialer main body 2 to prevent malfunction of the dialer main body 2.