BT style phone master socket.
The NTE5A master telephone socket provides a clear demarcation between the telephone operators network and the customer extension wiring via a removable connection unit (lower half). The product also provides line test, ringing components and over voltage protection.
The NTE5A features a BT601A socket (4 wires connected) on the front for connection of telephone apparatus as well as an IDC connection on the rear for extension wiring.
N.T.E. stands for Network Terminating Equipment