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Chapter 2: Introduction
2.2.4 C
ALLING
Y
OUR
S
UPPLIER
If you determine that your ISDN TA/V is malfunctioning,
do not attempt to alter
or repair the unit
. It contains no user-serviceable parts. Contact your supplier.
Before you do, make a record of the history of the problem. Your supplier will
be able to provide more efficient and accurate assistance if you have a
complete description, including:
• The nature and duration of the problem.
• When the problem occurs.
• The components involved in the problem.
• Any particular application that, when used, appears to create the problem
or make it worse.
2.3 Some Background Information About ISDN
ISDN (Integrated Services Digital Network) is a public switched digital
network which enables voice, data communications, video and many other
services, to be transmitted simultaneously over a single pipe consisting of two
64000-bps streams and a 16000-bps control channel.
The two 64000-bps streams are known as the bearer channels (B channels for
short; B1 and B2), with the control channel being referred to as the D
channel.
Your ISDN TA/V is approved for connection to an approved ISDN-2 service,
operating at data rates of 64000 bps, 56000 bps, 48000 bps, 38400 bps, 19200
bps, 14400 bps, 12000 bps, 9600 bps, 7200 bps and 2400 bps. Each of the two
B channels supported on a single ISDN line can be associated with either the
DTE interface or the telephone socket within your ISDN TA/V, and as such
provides you with simultaneously active data and voice channels.
B channel selection is handled automatically by the ISDN TA/V, and is totally
transparent to the user.
