PURPOSE: To dispense with the production of a main body part classified by every standard of a line by replacing a plug-in unit with specification suitable for the standard at every standard of the line to be connected and a memory in which a line control program suitable for the standard is stored.

CONSTITUTION: A hybrid circuit 4 is connected to the modem of the main body part 30 via diodes 5, 6, and issues output from the modem of the main body part 30 to the line 40 with an appropriate level, while, it receives a signal from the line 40 and outputs it to the modem. A ROM 10 storing the line control program to control a line interface unit(LIU) 20 according to the connection procedure of the line 40 is connected to the main body part 30 with an address bus 11 and a data bus 12. Thereby, it is possible to dispense with the production of a part regardless of the standard of the line classified corresponding to a shipping destination country.