We have thoroughly pursued the conventional technology
of the 4-line type sound weight tone control system in order
to polish up its performance. As a result, we have managed
to achieve a tone response performance ten times better
than that of the conventional system.We have applied for
a patent on our real tone system for other line simultaneous
call indication.This system has become a niche product and
is employed by leading makers such as NEC, Toshiba, Hitachi
International Electric, Nippon Musen, etc.