Remotes Connected with PRI via IP circuit emulation complaints of echo

[jarodwinters]

We are in the process of replacing an ATM network with an IP soultion to connection an 81 with about 12 Opt 11 via PRI. We are using Cisco gear to the do the circuit emulation via IP. Customer is complaining about intermitten echo on calls. Opt 11 has no local dial tone, all calls go out the TIE PRI to the 81 and out the local PRI. 4 digit dialing across the network via IP is fine, no echo, just local and LD and Tollfree which all use the same PRI out of the 81. Are there any settings in the 81 or 11 that can be tweaked for jitter buffer or echo cancelling? My first thought is that there may be a bad channel on the PRI but have not tested every channel yet using a maintence set.

 

[don2119]

I am pretty new with voip, but in Element manager under configuration Tab -vgw and ip phone codec profile you can enable echo cancellor and change the settings. I would definately also check the PRI lines like you said to see if any are giving you issues. You may also need to call Cisco about their settings for Echo cancellation. I have a similar set up to you I have option 11 remotes about 6 but they are connected to the CS1000MG via fiber and my locations with the Voip phones are also connected through a fiber network. And they do use Cisco POE switches, but we never had to tweak them. Is the problem system wide or is it certain phones or locations?

 

[jarodwinters]

Thing about this is there are no IP phones. We are just connecting opt 11 with an 81 using their existing fiber network. It was all based on ATM using LS1010 and MGX 8540. Now it is being converted to IP using a Cisco 2821 with a CEM T1-E1 card. We are not using Element Manager. I have been doing some testing and it appears to be an issue when dialing to or from an analog device both inside the system and outside. I can call from 2616 to 2616 out and back in and the call is clear. I can call from 2616 to an office which has a PRI and is clear. I call from 2616 to a 1fb like at home and there is an echo. I can call from an analog device on the system to a digital set on the system across the TIE lines and there is an echo. It appears to be a jitter buffer issue. We had the jitter buffer set at 80 and lowered it to 30. Cleared it up almost completely. Still just a little metallic sounding. Since lowered to 10 and 5 and has cleared ip up about %99.5. Just wondering if there are any tweaks on the Nortel side I can look at.

 

[don2119]

Only ld 117 are your ethernet commands and you can change intra and inter band widths,but zones would have to be used.
This is on release 4.5software I dont know what you are on. But since everything is just working over Cisco I do not know of anything you can do there. The only thing you might look at is how the PRI itself is set up in ld 17 under ADAN.
Outside of that I do not no anywhere else to look.

 

[jarodwinters]

Changing the jitter buffer down caused some other issues. Circuit wont stay up. Had to bump it back down to stablize circuit. They are running Sucession 3.0. No zones are configured. That should not come into play. Its just a tie line across an IP network. May have to check with Cisco TAC or Nortel tech support. Not having much luck today.

 

[don2119]

I am sorry I could not be of more help I think the path of going to Nortel and Cisco in this case is the way to go.If you do get an answer please post it so if we run into this again it will jar our memories. The only other thought I had was possibly a bandwidth issue.

Thanks.

 

[jarodwinters]

Searching the forums now to see what I can find. Will repost if I find a fix.

 

[tnphoneman]

I have seen this on a Mini Remote and a point to point t1 and the carrier had to put echo cancelers on the voice channels. Do not put it on d channels.

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[jhenley]

As a test with our carrier remotes, using a cisco2651xm for the most part did the same thing you are doing with the same analog echo issue results. Adjusting jitter did improve the problem. We also discovered that the remote would not recover on its own if it went down and had a later vintage card "D" I think, on the remote end. It has been a couple of years since we worked on this. We worked with Cisco and never could totally resolve the issue. We did not contact Nortel since we figured they would say it is not a supported product. As a result, we just use this IP solution in emergency situations for any of our carrier remotes in the event carrier issues occur for an extended period of time. This has provided service a couple of times when there was a major cable outage in the area.

JHenley