connection point in the ISDN network

The next connection point in the ISDN network is:

Network Termination type 1 (NT1) or

Network Termination type 2 (NT2) device.

These are network-termination devices that connect the four-wire subscriber wiring to the conventional two-wire local loop.

The NT2 is a more complicated device, typically found in digital Private Branch eXchanges (PBXs), that performs Layer 2 and Layer 3 protocol services. An NT1 / 2 device also exists; it is a single device that combines the functions of an NT1 and an NT2.

In North America, the NT1 is a Customer Premises Equipment (CPE) device. In most parts of the world besides North America, the NT1 is part of the network provided by the carrier.

ISDN service providers use a variety of switch types for their ISDN services. It is important that the correct switch type is configured on the ISDN device. This information is provided by your Internet Service Provider (ISP).

The most common type in the United States is AT&T's 5ESS and Nortel's DMS-100. Services offered by carriers vary greatly from nation to nation and region to region.

Like modems, each switch type operates slightly different and have a specific set of call setup requirements. You must be aware of the switch types used at the your CO (central office).

This information is specified during router configuration so your router can place ISDN network-level calls and send data.