AT&T MERLIN LEGEND Release 4.0 Feature Reference page 422

Feature Reference
ESF framing should be used to take advantage of its improved maintenance,
diagnostic, and testing capabilities. If the transmission between two systems is
voice-only, RBS should be used for all 24 communication paths. For voice
transmission, both ZCS and B8ZS line coding can be used to satisfy the
ones-density requirement: the preferred line-coding format is B8ZS, which is
needed for 64-kbps digital data.
The framing and signaling formats depend on the network and interconnection
devices (CSUs) used. For example, the 551 T1 L1 CSU only supports ZCS line
coding.
NOTE:
Digital data using up to 64 kbps is possible only through PRI when using a DS1
facility. (Connections of up to 64 kbps per channel are also possible on BRI
connections in Release 4.0 systems.) Also, ESF framing mode, CCS signaling,
and B8ZS line coding are required. An ACCULINK 3150/3160/3164 or ESF-T1
CSU must be used for DS1 connections within a building.
PRI Programming Options
The following options should be programmed for PRI facilities connected to a
100D (DS1) module.
PRI Telephone Number
The PRI telephone number is a string of up to 12 digits (any combination of
digits 0 through 9) assigned to each PRI line. This string is matched to the
Called Party Number sent by the network that indicates the number dialed by
the outside caller. The communications system uses this number to send the
call to the correct personal line button.
Network Services Supported
This option specifies the type of network service provided by each B-channel
group. The choices are as follows:
Megacom WATS
Megacom 800
MultiQuest Service
ACCUNET Switched Digital Service (SDS)
Software-Defined Network (SDN)
OUTWATS
INWATS
56/64 Digital Data
Virtual Private Network
Call-by-Call
Other
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Primary Rate Interface (PRI) and T1