Echo, SCN, VCM, all that good stuff

[yankblan]

I have an echo problem, and I have potential culprits, but not sure of anything:

Site A has an IPO 8.0, 2 combo cards. The good one has all 4 lines on it; the bad one (from last year's batch) only has a doorphone through a CO port on it. Phones are legacy Nortel phones. Everything running smooth.

Site B has a 7.0 (latest patch), one (good) combo card with an emergency local line on it. They are using 1608 phones. They sometimes have echo, specifically on long distance calls (according to them; I call BS on the last part).

They are linked through SCN. All external calls come/go through site A. The combo card on site B provides the VCM channels for the 1608s, and like I said, it is a new one.

2 things I don't know: is VCM only for IP to digital sets, or does it handle SCN too? If so, I suspect the bad combo card on site A; when they use a VCM channel from that card, they get the echo, if not, it's ok. I know the bad batch of combo cards had problems with analog trunks and VCM channels.

I rarely see echo problems on IP Office that I can't tweak; this one tried many things but can't get a finger on it.

 

[amriddle01]

If they are on the same codec they will either be DMP or RTP relay through the system for SCN calls, this can be seen/confirmed by watching the call in SSA

 

[yankblan]

You mean observing a call on the h323 trunk, under lines?

What should I be looking for?

 

[cormierjimmy]

Hi, I've a ticket open with a national provider and we are working on patchs. 8.0(46xxxx)

Problem is mostly on Combo Cards,
Headset can must be certified by avaya, Some headset generate echo and make VCM processor crazy
NLP confort noise can be set at -33db
All lines including analog bust be 0DB at a-d and d-a

The other problem I try to work with Avaya is the delay on SCN trunk, With Wireshark I can see bad RTP stream as you can see into system status

If your network is ok, I dont think you can do better for now.... open a ticket at Avaya

Jimmy Cormier, Quebec City, Canada
Sorry, I’m french !
15xBCM/SRG,CS1000,23xIP Office,14xVmpro,
10x contactstore,Call Manager,AES,Nice Recording,Callsweet,IEX Totalview,Symposium,Callpilot,Kofax,

 

[yankblan]

Salut Jimmy,

Je vais vérifier l'histoire des casques. Pour le d-a a-d, on le met généralement entre 3.0 et 3.5; plus bas que ça on a de l'écho sur les postes réguliers aussi.

Le seul problème que je vois via system status est le jitter buffer, qui n'a rien à voir avec l'écho, et apparamment les lectures là-dessus sont pas vraiment fiables.

Merci!

 

[yankblan]

If they are on the same codec they will either be DMP or RTP relay through the system for SCN calls, this can be seen/confirmed by watching the call in SSA


Do you mean delay?

Can you confirm that SCN calls do or do not use VCM channels? I'm thinking if it does, incoming should use site A (bad card side) VCM, and outgoing use site B (local/good card) VCM channels.

Also it's hard to diagnose with SSA since it installs in French because of my PC's OS.

 

[amriddle01]

No, I mean relay. Why do you have a French OS if you can't understand it?