To cancel, press the DND button again, and the light will no longer be lit. HOLD button will slow flash. Reply hands free or lift the handset. If switch is in this position, you will hear double bursts of intercom tone ringing and the HOLD button will slow flash. HOLD button will slow flash.
External conference allows up to one internal and two external.
Lift the handset and dial station number or desired outside party. When first called party answers, press CONF button. Add another conference party call by dialing another station number or outside party. When party answers, press CONF button. All parties are connected.