EMS4001 Expansion Master Station

The EMS-4001 adds four powered intercom channels to an MS-2002 or MS-4002 Master Station, and it provides talk, listen and call buttons for the added channels. Up to four EMS-4001 Expansion Master Stations may be connected to the MS-2002 or MS-4002 to can add up to 16 channels (20 channels total). The MS-2002 or MS-4002 microphone is used to talk back to the EMS-4001 channels, and the MS-4002 speaker is typically used for listening. However, there are also separate speaker jacks on the back pane...