EuroISDN is now the standard in most parts of the world, except North America
and certain other countries.
The EuroISDN network is supplied to the user through a box mounted on the
wall. This box is called a Network Termination Type 1 or NT1.
The NT1 is part of the network and is the point at which the network service
In North America (and some other countries) ISDN is supplied as a passive
socket terminating the circuit to the ISDN service provider.