The Valcom 24 Station Expandable Talkback Intercom System Expansion Unit provides 24 stations of handsfree intercom with one-way group call and all call. Up to three expansion units may be connected to provide 48, 72, or 96 zones of paging with handsfree reply, up to 16 one-way page groups, and all call. The system also provides the ability for a remote speaker location equipped with a call button to call the attendant location.