2 WIRE handsfree internal unit for wall mounted or table-top installation (with specific support to be purchased separately). Keys available: entrance panel/scrolling activation, door lock release, staircase lights control and handsfree connection. LEDs used for: call exclusion, door status, connection with the entrance panel. Independent adjustment for: bell volume (with call exclusion) and loudspeaker volume. 16 different ringtones available For wall mounted installation, the bracket supplied must be used.