AT&T MERLIN LEGEND System Reference Manual page 497

Functional Description
T1
4-28 DS1 Facilities
Any combination of the following AT&T Switched Network (ASN) Services can be
provided through a T1 or ISDN-PRI line/trunk
Megacom® WATS service for domestic long-distance outward voice calls;
ISDN-PRI on the MERLIN LEGEND Communications System does not
support access to international Megacom WATS service.
Megacom 800 for domestic toll-free incoming voice calls. lSDN-PRl on the
MERLIN LEGEND Communications System does not support access to
international Megacom 800 service. T1 service supports Megacom 800 with
or without Dialed Number Identification Service (DNIS), while ISDN-PRI only
supports it without DNlS. DNIS is a service provided by the AT&T Switch
Network that routes incoming 800 or 900 calls according to customer-
selected parameters, such as area code, state, or time of call. For example,
a customer can specify that calls received from a particular area code
should be routed to a specific individual or group responsible for accounts in
the area.
Software Defined Network (SDN) — AT&T Switched Network (ASN) service;
for voice and circuit-switched data calls (up to 56 kbps). SDN lets
businesses use portions of the ASN in concert with their dedicated private
line networks. However, the system does not support "uniform dialing plan,"
which is necessary for complete integration with SDN. lSDN-PRI on the
MERLIN LEGEND Communications System does not support access to
global SDN service.
MultiQuest for domestic toll incoming voice calls (900 number). T1 supports
MultiQuest with or without DNIS, while lSDN-PRI supports only it without
DNIS.
In addition to these ASN services, T1 also supports Shared Access for Switched
Services (SASS). SASS allows both Megacom and Megacom 800 services to be
offered over the same line/trunk facilities, eliminating the need to have separate
incoming and outgoing line/trunk groups.
Like T1, lSDN-PRI also supports Megacom WATS and Megacom 800 on a
shared line/trunk, but only on a call-by-call basis. Besides this, lSDN-PRl
provides Accunet® switched digital service for 56-kbps, 64-kbps restricted, and
64-kbps clear circuit-switched data calls. ISDN-PRI on the MERLIN LEGEND
Communications System does not support access to international Accunet
services.
T1 is the factory setting and is selected for the DS1 facility to allow each of the
24 channels to be programmed to emulate tie, loop-start, or ground-start
lines/trunks in any combination. This means that a single 100D module can take
the place of 24 regular outside lines.
If common-channel signaling is selected, 23 channels are available for
emulation and the 24th channel carries formatting signals.