MERLIN LEGEND Communications System Release 6.1 | | Issue 1 |
Network Reference 555-661-150 | | August 1998 |
5 Network Management | | |
| Tandem PRI Facilities | | Page 5-22 |
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| Tandem PRI Facilities | 5 |
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This topic presents considerations for managing tandem PRI facilities connected to your local system in a private network.
If your system includes PSTN PRI facilities that route calls to non-local extensions, you also need to consult the procedures in the “Dial Plan Routing” topic of “PRI Facilities,” System Programming. You can, if necessary, delete all the digits from PRI calls received on a system and substitute the non-local extension number (calling group number, for example) required for routing across the private network.
When you order facilities for PRI, you specify a T1 point-to-point circuit; the service provider may supply amplification but not PRI service or switching. Program the circuit for PRI, following the instructions in System Programming for both DS1 and PRI. Tandem PRI trunks should be programmed for Extended Superframe (ESF) format, which detects errors more reliably than other formats. In addition, tandem PRI trunks should be programmed for bipolar 8 zero substitution (B8ZS) line coding. If alternate mark inversion (AMI) line coding is used, 64-kbps data calls (128 kbps for 2B data) are not supported. If D4 framing is used maintenance is more difficult. The framing and line coding must be verified with the service provider. However, 56-kbps data calls are supported (112 kbps for 2B data).
NOTE:
Verify that any Channel Service Unit (CSU) on the DS1 circuit between the MERLIN LEGEND Communications System and the PSTN is programmed for the same framing as the DS1 slot on the MERLIN LEGEND Communications System.
You may place drop-and-insert equipment between systems connected by a PRI tandem facility, allowing use of fewer than 23 B-channels. Some channels are reserved in this way for non-MERLIN LEGEND communications, and the remaining are dedicated to MERLIN LEGEND voice/data traffic. The equipment must never drop Channel 24, the D-channel. All 24 channels still count toward the system maximum of 80 lines. For channels not used by the MERLIN LEGEND system, lines and B-channels must be removed from the B-channel group.
NOTE:
When connecting to a DEFINITY ECS or DEFINITY Prologix, the DEFINITY must provision all 23 B-channels and allow MERLIN LEGEND to take out of service any B-channels that were dropped, then DEFINITY can unprovision those channels.
