Nortel BCM 3.7, Manual

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534 Understanding MCDN network features
N0008589 3.3
ISDN Call Connection Limitation
The ICCL feature piggybacks on the call initiation request and acts as a check at transit PBX
points to prevent misconfigured routes or calls with errors from blocking channels.
This feature adds a transit/tandem counter to a call setup message. This counter is compared at
each transit PBX with a value programmed into the transit PBX, in a range from 0 to 31. If the call
setup counter is higher than the PBX value, the call will be blocked at the PBX system and cleared
back to the network. This prevents calls from creating loops that tie up lines.
Business Communications Manager configurations:
• Under Network Services, MCDN , set NtwkICCL to Y(yes).
• Under the media bay module record for the trunk module, define Maximum transits.
The following figure demonstrates how a call might loop through a network if the system is not set
up with ICCL.
Figure 185 Call loop on system without ICCL
Business Communications Manager
Meridian 1
Telephone A
Business Communications Manager
Business Communications Manager
Meridian 1