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What does ISDN give you? - 1

There are two forms in which ISDN is supplied.

Basic Rate

• Access to the network is called Basic Rate Access (BRA).

• It is provided through a Basic Rate Interface (BRI).

• This kind of interface is also called an S

Interface.

• There are two channels that you can use.

Primary Rate

• Access to the network is called Primary Rate Access (PRA).

• It is provided through a Primary Rate Interface (PRI).

• This kind of interface is also called an S

Interface.

• There are either 30 channels (most of the world) or 23 channels (North America,

Japan) that you can use.

What does ISDN give you? – 2

Basic Rate

• The total data rate across this interface 144 000 bits per second.

• This bit rate was chosen because the wiring already installed by the telephone

companies under the streets can carry baseband

(digital) transmission at this

speed.

Primary Rate

• The total data rate across this type of interface is 2 048 000 bits per second (2Mbits

per second) in Europe. In North America and some other countries the total data

rate is 1 536 000 bits per second (1.5Mbits per second)

• This kind of access requires the installation of a high-speed line to the customer

premises.

Normally, Basic Rate would be for domestic use, telecommuters or smaller remote offices.

Primary Rate would typically be used for large remote access servers, fax servers or PBX

in medium sized or large offices. For instance, most ISPs (Internet Services Providers) use

PRI lines to provide dial-in analogue and ISDN connections for their subscribers.

ISDN Services

There are two kinds of services provided by ISDN.

Network services

• Network services carry the interactions between the user and the network

• For example: setting up calls and disconnecting them

Bearer services

• Bearer services carry data between two users

• For example: voice or fax information encoded as a bit stream

Network Services

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Eicon Networks ISDN NT1 Specifiche Pagina 3