Our new upgrades have announcers with 2-way intercom programmed into the control panel as well. User presses a button and the device calls a designated number, plays a recorded announcement and then opens up the mic to there can be a conversation.
The older ones have cheap analog trimline phones in them that are programmed to off-hook dial the chosen destination, which must have a display to show where the call is coming from or the inspector (as of just recently) gets whiny.