A wide bandwidth coupler has two outer elements around a center element. The apparatus includes a hinge gap blocker for use with an existing door and door surround configured to continuously occlude a gap between the door jamb and the outer facing edge of a door hinge stile. A distance is ensured between the first and second bases, and when the two moving elements move between the first and second bases, both a guide surface of the first base and a guide surface of the second bases are used. Signaling System 7 of the Common-Channel Interoffice Signaling system is used for digital signaling between the SCP and the SSP. The arms are also selectively lockable at two or more angular positions relative to each other.