Nortel BCM 3.7, Manual

Page: 243 / 1004

Understanding how the system identifies lines 243
Programming Operations Guide
Business Communications Manager systems or Meridian 1-IPT systems. Note: SIP trunks can
only be used between Business Communications Managers.
You can also create a fallback for the trunk. This is a situation where the system reroutes the call to
a PSTN line pool if the primary route is not available or the call quality is not suitable. If you do
not configure your network for fallback and the call quality is below threshold, the IP call fails.
Refer to the IP Telephony Configuration Guide for information about configuring VoIP trunks.
Target lines
Target lines are internal communications paths that directly connect auto-answer trunks to system
telephones. These lines are in-coming only.
Target lines allow you to make more efficient use of DID line resources.You can map a range of
target lines for each DID line. The incoming call is routed according to the mapped dialed digits,
rather than a one-to-one line assignment. Refer to
“DID system” on page 203 for an example of a
system using DID trunks and target lines. Systems configured using the DID template,
automatically assign target lines to all assigned DNs.
You also require target lines when you use PRI or VoIP trunks.
Target lines use line numbers 241 to 492. These lines are found under Services, Telephony
Services, Lines, Target Lines . Record this information in your system Programming Records so
you have a clear view of where each line is assigned.Refer to “Assigning target lines” on page 297
for instructions about setting up target lines.
Other features:
• Each target line also can be assigned to more than one telephone.
• A telephone can have multiple appearances of a target line.
Physical lines
Physical lines are the central office (CO) trunks assigned to the trunk media bay modules. Which
lines are enabled is determined by the DIP switch settings on the installed trunk modules.
You can change the line types to suit your system. For instance, BRI and DTM modules can be
designated to a number of line types, depending on the type of line service provided through the
central office (CO). However, the line numbers are associated for specific tasks or to specific
DS30 bus numbers.
Refer to the table below for a list of lines assigned per bus (DS30 bus and offset), based on the
module type configured with that address. You can use this chart to note which lines should be
active for the modules you installed. You can also note which line pool you put the lines in, and
note the line pool access codes or routes and destination codes to which you assigned the line pools
(or use your programming records).