Lucent Technologies MERLIN LEGEND Release 5.0 Feature Reference page 488

MERLIN LEGEND Communications System Release 5.0
Feature Reference 555-650-110
Features
Primary Rate Interface (PRI) and T1
Table 31.
Setting
1
2
3
4
5
Signaling Mode
Signaling is the process of communicating channel-state information, such as
dialing, from endpoint to endpoint. Two types of signaling can be used in T1
transmission: robbed-bit signaling (RBS) and common-channel signaling (CCS).
Choosing a signaling mode is important only for T1 service; PRI always uses CCS
(23 B-channels and 1 D-channel). The signaling types are as follows:
Robbed-Bit Signaling. Robbed-bit signaling (RBS) replaces the least
significant bit in every sixth frame of each DS0 channel with signaling
information. RBS is also called in-band signaling because signaling
information is embedded in the same channel that carries the user's voice
or data in a call. Robbed Bit Signaling must be used if T1 Switched 56
service is to be used on the T1 connection.
Robbed-bit signaling is appropriate for voice and voice-grade data, and
digital data on channels programmed for T1 Switched 56 service.
Common-Channel Signaling. Common-channel signaling (CCS) is an
out-of-band signaling format that places the signaling bits for channels 1
through 23 into the 8-bit word of the twenty-fourth channel. This restricts
DS1 from using the twenty-fourth channel for voice or data transmissions.
D4 framing does not preclude the use of CCS, but CCS is not compatible
with D4 channel banks because the D4 channel banks recognize only
RBS. CCS is used when PRI service is desired on the DS1 facility.
ESF framing should be used because of its improved maintenance, diagnostic,
and testing capabilities. If the transmission between two systems is voice-only,
RBS should be used for all 24 communications paths. For voice transmissions,
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.
NOTE:
Through PRI, digital data using up to 64 kbps is possible only when using a
DS1 facility; connections of up to 64 kbps for each channel are also
Line Compensation Settings
dB Loss Cable Length (22-Gauge Wire)
0.6 0–133 feet (0–40.5 meters)
1.2 133–266 feet (40.5–81 meters)
1.8 266–399 feet (80–121.5 meters)
2.4 399–533 feet (121.5–162 meters)
3.0 533–655 feet (162–199.5 meters)
Issue 1
June 1997
Page 456
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