PURPOSE: To inexpensively and accurately set a level by limiting the amplitude of a signal, which is sent to a telephone network after executing the A/D conversion, storage and D/A conversion to a signal from the telephone network, lower than the effective value of difference between an allowable maximum value and the gain of a network control means.
CONSTITUTION: A network control means 11 controls the connection of a call while connecting an analog telephone network and provides I/F with the telephone network concerning an analog audible frequency signal A to be exchanged as a message during communication. A message storage means 13 performs A/D conversion to the signal A from the means 11 and stores it as digital information D and a message sending means 15 outputs the signal A for which D/A conversion and reproduction are executed to this stored information D. At such a time, an amplitude limiting means 17 of the means 15 limits the amplitude of the signal A within a range lower than the effective value of difference between the allowable maximum level of sending the signal A to the telephone network and the gain of the means 11 in the area of the information D. Thus, man-hour for design and manufacture can be reduced and the output level can be stably set with high accuracy.
HIROTA YASUO
ASANO MASABUMI
OKAMOTO RIKIYA
INABA SEIJI
YAMAGUCHI TOSHIYUKI
KANEKO YUICHI
UENO MASAHIRO
ITO ATSUSHI
IMAZATO TAKASHI
