Introduction to the Pipeline
ISDN basics
1-6
Preliminary January 30, 1998
Pipeline Start Here Guide
ISDN basics
Ordering ISDN service is called “provisioning the line.” If you need help
provisioning your ISDN line, refer to Ascend’s web site at www.ascend.com,
where you can find a web page all about provisioning an ISDN line in North
America. Additionally, Ascend’s Technical Assistance Center can give you all
the information you’ll need when you talk to your phone company.
If you need help with some of the terms associated with ISDN or with basic
networking functions, please see the Networking Glossary on the Pipeline
Companion CD. The Networking Glossary is an HTML title that you read with a
web browser. Refer to the A-to-Z section for an explanation of hundreds of terms.
The Networking Basics section illustrates how ISDN and other networking
functions work.
Basic Rate Interface (BRI)
When you order ISDN service for your home or office, you get what is known as
Basic Rate Interface. This gives you three channels: 2 B channels with a capacity
of 56 to 64 Kbps each (depending on the service offered by your telephone
company), and a single D channel with a capacity of 16 Kbps.
Whenever you make an ISDN call, you start by using one B channel. If the
receiving end can accept the second B channel, and if the data requirements of
your call need the extra bandwidth, your Pipeline uses the second B channel. You
can set up the Pipeline to use only one B channel when connecting to a given
phone number. Using the second B channel costs more. Sometimes there is a
premium charge from the phone company for the first minute, so be aware that
bringing up two channels can cost more even though the call is shorter. Check
with the remote end to see if there are additional charges when connecting with
both B channels, and make sure the remote end can handle a two-channel call.
The D channel is a 16 Kbps service that is used to manage the administrative
tasks required by the ISDN service. It sets up calls, adds the second B channel,
and clears calls. It is always a “live connection” so some services make use of it
to transmit light traffic, such as credit card transactions or email notification.
