Echo & noise on off-site calls

[jwadswor]

Some of our users are experiencing noise on the line when making (not usually receiving) off-campus calls. It *never* happens when it is from another station on the KSU.

The noise will sometimes be a strong echo that only the user here hears (the other party does not hear it), or a 'dead silence', where our user hears silence, but the other end thinks everything is okay.

Also, it seems to be more with some users than others. Some say they rarely make a call that they don't have problems, some never complain. I know this could just be the fact that different people notice different things, but I thought I'd mention it.

It sounds to me like either a telco problem, or a configuration issue with the T1.

Any ideas?

BTW, we are operating on a MICS, S/W rev 4.1, and the incoming/outgoing lines are via a T1, not sure how it's configured.


Thanks as always for your invaluable insight!!

Jon

 

[LKev]

My guess would be if you are using a T-1 for outdialing that it is a provider problem. What I think you are having a problem with is called (echo cancellation) in regards to the programming of the T-1. Call you provider, and have them check that. Hope that helps.

 

[AlquestTech]

Did you ever resolve this problem?

We are having similar issues on PRI's going through Cisco routers.

But the problems are exactly the same.
Localized to a few users. Only calls through PSTN and only at our users end. Usually disappears after the first few seconds.

We have adjusted VAD settings and playout delay on Cisco Routers and a few others, and it has reduced some, but not for all users.

also it seems to hapen only with certain calls in but not localized to one specific area.

 

[jwadswor]

Alquest -
Our problem never did get completely solved; I still notice the problems almost daily, but we replaced the telephone set of the user who had the biggest problem with it, and now she is doing much better.

So no, I guess we didn't come up with a real solution.

As to your situation, if you are going through Cisco routers, is that a VOIP environment? Have you eliminated problems with the VOIP? If it's really a PRI issue, let me know if you ever come up with something!!


Jon

 

[AlquestTech]

Yeah - as you can see, it gets tricky as it is partly a VOIP issue and may also be a T-1/PRI issue.

I forget what the equation is, but echoe is basically a function of distance and level (If I remember correctly)

I did also find that by rerunning a few cables (with less interferance) we were able to clean up signals and eliminate some echo (background hiss as well).

If I ever get it nailed completely, I'll post.

Thanks