The MC34216A is developed for use in telephone applications where, besides the standard telephone functions, the group listeningin feature is also required. In cooperation with a microcontroller, the circuit performs all basic telephone functions including DTMF generation and pulsedialing. The listeningin part includes a loudspeaker amplifier, an antihowling circuit and a strong supply. In combination with the TCA3385, the ringing is performed via the loudspeaker. Programmable DC Mask, for France, U.K., and Voltage Regulated Countries