Trunk Operating Modes (T1); Ground Start Trunks (T1 Only) - Nortel Modular ICS 6.0 Installer's Manual

72 / Trunks and target lines
one or more telephones. Target lines are numbered 157 to
348 in a fully expanded system, and 157 to 284 in all
others.
Telephones can be configured to have an appearance of any
type of trunk and line, including target lines, but excluding PRI
trunks. If assigned, they are used for monitoring call usage.

Trunk operating modes (T1)

T1 trunks have four operating modes:
• ground start (T1 only)
• loopstart (analog and T1)
• E&M (analog and T1)
• DID (analog and T1)

Ground start trunks (T1 only)

Ground start trunks offer the same features as loop start trunks,
but are used when the local service provider does not support
disconnect supervision for the digital loop start trunks. Ground
start trunks work with T1 only.
By configuring lines as ground start, the system will be able to
recognize when a call is released at the far end.
Tips -
start trunk on a DTI. It always has disconnect supervision.
A DTI can provide a maximum of 24 ground start trunks.
Analog ground start trunks are not supported.
Modular ICS 6.0 Installer Guide
You cannot change the trunk mode for a ground
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