Dropped audio on pbx

[tentrees]

We have an NEC Electra Elite looking into a fractional T1 for voice. About 6 months ago it started dropping our end of the conversation.... that is, the caller could not hear us but we could hear them..... Phone vendor, communications provider and carrier techs have all looked at problem with no solution.... concensus is that the pbx is causing the problem... Phone vendor has replaced many cards, chassis, and reprogrammed it several times to no avail....

We have found that when problem occurs, if we place call on hold momentarily then retrieve call, problem resolves....

Any ideas on the cause?
john

 

[Trotski]

does it happen on all handsets

 

[tentrees]

Yes, it happens on any of 30 handsets.... no corelation with time of day, type of call or anything else I can see.

 

[ISDNman]

>>>We have found that when problem occurs, if we place call on hold momentarily then retrieve call, problem resolves....<<<

This proves it is the PBX, not the Telco. The Telco has no way of knowing you put it on hold.\

Almost sounds like a software bug. The system was not "upgrade" shortly before this started was it?

Best of luck.

 

[tentrees]

I agree that it is in the pbx.... I've forced them to replace it in it's entirety... hardware and software.
This is supposed to be done tomorrow...we shall see.

 

[Trotski]

Yeah, has to be related to the PBX

 

[strmwalker]

tentrees...is this a pri this is happening on or
copper trunks?if it is a pri then ISDNman what about
d channel messaging the co would when the call was put
on hold.

no problems only solutions

strmwalker

 

[donb01]

I was going to suggest that if your system allows you to mess with the trunk timing and signalling parameters that you look into that - putting the call on hold and then getting it back may be allowing the call to "resync" itself.

Now that you have replaced everything and all the settings should be back to default (assuming they didn't just restore a system backup off your old one) it's probably a moot point...

 

[tentrees]

The problem with dropped calls is resolved.... turns out the Phone vendor replaced two IAD(?) cards with two PVA(?) cards. Found out later (from NEC) that the PVA cards are not compatible with a IPK I cpu. Vendor changed the IPK I Cpu card with an IPK II CPU and the problem went away... I fault NEC for not suggesting this weeks ago. They know it is a problem but dropped the ball big time.

We will be adding two more PBX's at new facilities and I will be hard pressed to use NEC after this crap.

Thanks to all of you for the suggestions. Hope this resolution helps someone else.
john