PURPOSE: To reduce output distortion and noise in the case of absorbing the timing deviation of a write clock synchronized with input voice information and a read clock synchronized with an internal clock while performing stuff and skip operations by an asynchronous absorber at the time of fetching the input voice information in synchronism with the internal clock of a present station.

CONSTITUTION: When no input voice is present at a voice detector 9, the delay amount of a variable delay device 8 is reset to an initial value and also asynchronous absorption is performed while performing the normal skip and stuff control by the asynchronous absorber 2. When the input voice is present, while the delay amount of the delay device 8 is controlled instead of the stuff and skip control of the asynchronous absorber 2 corresponding to timing comparison signals (e), its output (k) is inputted to the asynchronous absorber 2 and the asynchronous absorption is performed. Since the skip and stuff control is performed when no input voice is present, the output distortion or the like are eliminated and since delay amount control is performed at other times, skip and stuff are not required.