Dolby Laboratories DP503 - Manual (Page 81)

APPENDIX D
ISDN ORDERING GUIDE (NORTH AMERICA)
D.1 Introduction
The following ISDN ordering guide is for Dolby Fax users ordering ISDN service
for the Ascend Multiband VSX ISDN terminal adapters/inverse multiplexer
(hereinafter referred to as the “ISDN unit”) that is used with the Dolby Fax system,
and is intended to provide answers to the basic questions that arise when ordering
ISDN service.
Tip: The most important rule when ordering ISDN circuits from the phone company is to be patient(!)
ISDN stands for Integrated Switched Digital Network. It is a low-cost bi-
directional digital data service that can transport any type of data, such as video,
graphics, and E-mail, for basically the cost of a regular phone call. Taking
advantage of the low-cost of ISDN, it is now also possible to economically send
CD-quality audio using Dolby Fax, originally with Dolby AC-2 digital audio, and
more recently with Dolby Digital (AC-3) and MPEG Layer II. ISDN allows high
transfer of data between locations without the usual problems associated with
regular phone lines. ISDN is currently available in all major markets around the
world.
ISDN BRI (Basic Rate Interface) is also referred to as 2B+D, which specifies 2 B
or Bearer channels each providing 64 kbps of voice or data and a D or Delta
channel which performs the dialing function. Technicians will typically refer to the
service as 2B+D, but either name is correct.
D.2 Ordering ISDN Service
When ordering ISDN from your local phone company, you will be asked specific
questions regarding the type of services available and equipment involved. For the
most part, the questions are all the same but may be worded a little differently. All
Dolby Fax ISDN installations have the following in common:
1. Specify the call types as Point to Point, not Point to Multipoint. This
means that you will only be connecting to one location during any one call.
Video conferencing systems utilize PTMP through bridges so that multiple
locations can participate in a video conference.
2. Choose the type of service as circuit switched as opposed to "nailed,"
leased or dedicated.
3. Specify the B or Bearer channels, usually referred to as B1 and B2, to be
defined as CSD or Circuit Switched Data, as opposed to CSV Circuit
Switched voice.
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