The MC34216 is developed for use in telephone applications where besides the standard telephone functions also the group listeningin feature is required. In cooperation with a microcontroller, the circuit performs all basic telephone functions including DTMF generation and pulse dialing. 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.