- Use with SIP (Session Initiation Protocol) VoIP PBXU- Use with Valcom multi-zone page control unit with Centrex or C.O. lines (DTMF signaling only)- Use with Valcom handsfree page units for talkback paging- Multiple units may be connected for multi-zone paging with all call behind a PABX- Background music stereo or mono input; music mutes during page- Volume controls for background music and tones- Security code option to restrict page access- Store and Play feedback eliminator option- Multiple disconnec