Lucent Technologies MERLIN LEGEND Release 6.1 Feature Reference page 251

MERLIN LEGEND Communications System Release 6.1
Feature Reference 555-661-110
Features
Digital Data Calls
The MLX extension numbers used to add 2B data capability must correspond to
the adjunct extension number for the MLX telephone. By default in a two-digit
numbering plan, these adjunct extensions are numbered with the digit "7"
preceding the two-digit extension number. If the MLX extension is 20, its
corresponding adjunct extension is 720. In a 3-digit or Set Up Space numbering
plan, the adjunct extension number is, by default, the main extension number plus
200. (For details about numbering plans, see
659.)
Once an MLX jack is correctly programmed, a 2B data-capable device properly
connected to the jack should operate at the same data rate (up to 128 kbps) as an
NI-1 BRI line connected directly to a central office.
2B data calls are really two calls, one for each B-channel. (Similarly, ISDN
terminal adapters that connect to V.35 video systems must make and receive two
calls in order to provide double the speed of a single digital call.)
NOTES:
1. Users can use any combination of PRI, NI-1 BRI, and T1 to obtain a
2. In Release 6.0 and later systems (Hybrid/PBX mode only), MERLIN
Considerations and Constraints
When a desktop video system is in a passive-bus configuration (that is, an MLX
telephone is connected to it), and the connected MLX telephone is using one of
the B-channels for any reason, the desktop video system can receive a call only
as a 1B data call. (Some video systems do not support 1B data.) This is called
B-channel contention and can cause problems with features that require two
B-channels, such as Voice Announce to Busy, Hold (including Hold for transfer or
conferencing), Call Waiting, and Automatic Callback.
Features that redirect calls (for example, Coverage, Forwarding, Data Hunt
Groups, and Night Service) can present problems for 2B data calls. For example,
a video system should not be a coverage sender because another video system
receiving calls for it can be assigned only one Cover button for the sending
extension. Therefore, only one call of a 2B data call is sent to the receiver, and the
2B data connection. However, data transfer speeds are slower on T1
Switched 56 lines (56 kbps on each line). Because of potential speed
and other conflicts, it is best to use the same type of facility for both
calls that make up a 2B data call.
LEGEND Communications Systems can be connected to one another
or to DEFINITY ECS or DEFINITY ProLogix Solutions systems in a
private network. If the tandem trunks connecting the systems are PRI
and two B-channels are available, 2B data digital calls between the
systems can take place at 128 kbps. If the tandem trunks connecting
the systems are T1-emulated tie data trunks and two channels are
available, 2B data digital calls between the systems can take place at
112 kbps.
"System Renumbering" on page
Issue 1
August 1998
Page 202