Dolby Laboratories DP503 - Manual (Page 83)

D-3
If your switch type is a Northern Telecom DMS-100, provide the following
information to your phone company regarding the ISDN unit:
Parameter Value Notes
Signaling Functional
Protocol Version
Control (PVER) 1 or 2 A value of 1 is NTI custom. A value
of 2 is National ISDN-1 (NI-1) and
also requires a TID to be assigned as a
suffix to a SPID.
TEI Assignment Dynamic
Maximum
Number of Keys 3 Note that any number that is greater
than one will work.
Release Key is N
or a Key Number No Note that the value of this field is not
relevant for proper operation of the
ISDN unit.
Ringing Indicator
is Y/N No Note that the value of this field is not
relevant for proper operation of the
ISDN unit.
EKTS is Y/N No
In addition to the DMS-100 or 5ESS switch types, NI-1 or National ISDN-1 is
another option or offering from the phone company. National ISDN-1 is a national
standard that includes compatibility with both switch types.
D.2.2 B Channels
The last question to ask is whether the B channels operate at 56 or 64 kbps; 64
kbps B channels operate under SS7 (System Signaling 7). The following is an
explanation regarding B channel data rates.
The Dolby Fax system, at the default data rate of 256 kbps for Dolby AC-2,
requires 256 kbps of bandwidth from the ISDN network to which it connects. With
ISDN BRI at 64 kbps per B (Bearer) channel, 2 BRI circuits are required which
provide 4 B channels for a total of 256 kbps. There are some parts of the country
that operate at 56 kbps per B channel. If you are within an area which offers 56
kbps B channels, such as GTE, or plan on making ISDN calls into an area offering
56 kbps B channels, then 3 BRI circuits are required.
The reason for 3 ISDN circuits within certain regions is due to the fact that B
channel access is limited to 56 kbps instead of 64 kbps. This means that a Dolby
Fax call into or from such regions requires 5 B channels instead of 4. The ISDN
unit takes 5 B channels at 56 kbps each for a total of 280 kbps and makes a 256
kbps call (creates a 256 kbps clock) by bit-stuffing the 24 kbps overhead of
bandwidth. Ascend refers to this as their Delta Mode call type.
MAIN