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Terminology

In this section you will learn:

• The naming conventions used within ISDN

• The essential difference between the key items

• The significance of the various reference points

• The practical implications of international variations

Where the network terminates: The NT1

Most ISDN services are provided through a device known as an NT1. This stands for

Network Termination type 1. The device is provided by your network operator and is part

of the ISDN. This is the point at which you access the network The upper picture on the

right shows the NT1 supplied by British Telecom.

In North America, the ISDN service provider does not provide the NT1 for you. You are

provided with a simple socket to which you may attach a single ISDN device. If you wish to

attach more devices, you must purchase an NT1 and connect it to this socket.

In most of the rest of the world, the NT1 is provided by the ISDN service provider and

normally has two sockets into which you can plug ISDN devices.

The NT1 is an active device, with quite complex electronics that handle the transmission of

the 144kbps data stream to and from the ISDN service provider's switch or exchange.

An NT1 cannot make calls by itself. You need to plug in Terminal Equipment (TE) or a

Terminal Adapter (TA) to do anything useful.

Some NT1s (sometimes called NT1+ or Super-NT1) also have analogue ports on them so

you can plug in an ordinary analogue phone. The lower picture on the right is the British

Telecom Highway Super-NT1. The blue sockets provide ISDN; the white sockets are for

connecting analogue devices.

Types of equipment that can be connected to ISDN: TE & TA

Terminal Equipment Type 1 (TE1): understands how to interface to the ISDN network

o Can connect directly to the ISDN

o E.g.: ISDN interface card or USB device

Terminal Equipment Type 2 (TE2): understands nothing about ISDN

o Must use a Terminal Adapter (TA) in order to be connected to ISDN.

o Examples: modem, fax, analogue telephone, PC Serial Port. (Perhaps

even a television camera).

A Terminal Adapter is required to connect a TE2 device to the ISDN network.

A Terminal Adapter is by definition the equipment needed to connect a TE2 to an

ISDN.

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Eicon Networks ISDN NT1 Especificaciones Pagina 25