Have had numerous customers converting from PRI over standard T1 circuits to SIP. Either provisioned straight to PBX or onsite conversion from SIP to PRI. The issue I am having problems with concerns clock recovery. Any PBX must sync up with PSTN clock for stability, prevent clock slip, etc. I can't get a straight answer from the providers about clocking for the SIP-PRI provisioned circuits. They usually tell us not to worry about clocking. When I have tried to clock from one of these circuits I get mixed results, some will sync up, others not. I realize there are likely setting in the Cisco, Adtran, etc. gear that controls this but they don't seem to be very worried about this. Anyone with a better understanding of this or can direct me someplace. (nearest bar maybe) There is plenty of stuff about SIP on the 'net but not much about the physical provisioning or rules to follow. Mostly the marketing stuff, it's so great, will save you $$$, all the usual jazz.
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SIP trunking over PRI provisioning---clocking for PBX???
- Thread starter kevin906
- Start date
Generally, clocking only matters if the DS1 (physical pipe) is physically connected to the PBX. SIP is generally delivered across Ethernet. So, if carrier delivers calls to a gateway at your site, and the gateway hands to you as PRI, you'll collect clock from the gateway. If carrier hands SIP to you via Ethernet, they (or someone) will generally provide a router or similar device that will connect to DS1. You then connect PBX via Ethernet, so clocking isn't an issue.
As a rule, in my experience
SIP Gateway should provide clock to the PBX, UNLESS the PBX has an existing ISDN, then the PBX should take clock from this and the Gateway recovers clock. But it's down to your PBX config a lot of the time. Just make sure the Gatway's ISDN's know that it is A end or B end for each trunk.
Robert Wilensky:
We've all heard that a million monkeys banging on a million typewriters will eventually reproduce the entire works of Shakespeare. Now, thanks to the Internet, we know this is not true.
SIP Gateway should provide clock to the PBX, UNLESS the PBX has an existing ISDN, then the PBX should take clock from this and the Gateway recovers clock. But it's down to your PBX config a lot of the time. Just make sure the Gatway's ISDN's know that it is A end or B end for each trunk.
Robert Wilensky:
We've all heard that a million monkeys banging on a million typewriters will eventually reproduce the entire works of Shakespeare. Now, thanks to the Internet, we know this is not true.
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