PURPOSE: To obtain a facsimile adapter dedicated to a digital automobile telephone capable of realizing data transfer for mutual transmission rate conversion without placing any load on the microcomputer which controls the system.

CONSTITUTION: A timing generation part 5 generates a TCH compensating clock for the stop period of a TCH clock by utilizing the clock in the system. Then the writing and reading of a memory for the data transmission rate converting process are performed in synchronism with the TCH clock and TCH compensating clock.