AT&T MERLIN LEGEND Data Manual page 30

Data Communications with This System
See System Reference for detailed
information and programming
requirements for DS1 facilities.
The DS1 provides a digital signal so data calls from a digital station can be
placed to outside digital stations and transmitted at higher speeds (up to
56 kbps).
A DS1 facility provides either T1 or PRI access.
T1 is the factory setting. Each of the 24 channels can emulate any
combination of E&M tie, LS, or GS lines/trunks. A single 100D module can
replace 24 outside lines/trunks. T1 facilities are used to place and receive
data calls from outside analog data stations. Outside digital data
communications are not supported.
ISDN-PRI is the standard format for ISDN service. Any combination of the
following AT&T Switched Network (ASN) Services provided through an
ISDN-PRI line/trunk can be used:
Accunet® switched digital service for 56-kbps and 64-kbps restricted,
and 64-kbps clear circuit-switched data calls
Megacom® WATS service for domestic long-distance outward voice
calls
Megacom® 800 for domestic toll-free voice calls
Software Defined Network (SDN) for voice and circuit-switched data
calls (up to 56 kbps)
The benefits of ISDN-PRI include
Speed. Data calls to outside destinations can be made on the same
B channels used for voice calls if the service allows. Modems and
dedicated, conditioned lines/trunks are not needed.
AT&T's INFO-2 automatic number identification (ANI) service.
Customers who subscribe to this service can identify the caller on an
incoming call on an ISDN-PRI line/trunk by either telephone number or
billing number.
Note: The availability of the caller identification information may be
limited by local-serving (caller's) jurisdiction, availability, or central
office equipment.
Dynamic B-channel assignment. An individual B channel can be
removed from service without blocking calls to or from any other B
channels.
Improved toll restriction. Bypassing of toll restriction is limited on
ISDN-PRI lines/trunks.
Reliable indication of far-end disconnect. Blocking of incoming calls is
prevented because a line/trunk is not immediately released; instead
there is a delayed indication of disconnect.
Improved SMDR reports. Call timing for SMDR reports is improved
since calls recorded are closer to the actual billed duration.
Shared use of B channels for Megacom WATS and Megacom 800 on a
call-by-call basis for more efficient use of facilities.
Data Communications Components
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