Intermittent voice loss

[tim.miller@tnlottery.com]

I am using a 3300 ICP rl 5.0.1 and all of a sudden on some incoming and outgoing calls the caller cannot hear our voice but we can hear theirs.  We have replace DSP cards thinking that this would solve the problem to no avail.  Can anyone provide some ideas on what could be causing this issue.

[Mattmayn]

What type of trunks do you have?

[v2win]

What kind of phones?

What kind of trunks?

Are there any alarms on the system?

If they are IP phones have there been any network changes lately?

Does this happen internally on a station to station call or is it external calls only?

[tim.miller@tnlottery.com]

PRI Trunks

Digital and IP Sets

4000 series digital and  5215, 5240 Ip

No alarms on system or on NSU's

We have only been able to recreate internally station to station once.  I have been able to recreate the voice loss while on good calls by placing them on hold to get the channels where no outgoing voice consistently goes to silence.  I can always hear the other end.  There have been no network changes made to my knowledge.  I am responsible for those changes and we have done nothing.

[v2win]

In your testing do you happen to remember was it IP to IP or IP to TDM or TDM to TDM calls?

[Chakara]

  Can you explain this in a bit more detail:

while on good calls by placing them on hold to get the channels where no outgoing voice consistently goes to silence.

  Does this mean you can be on a working way audio call, you place the call on hold then retrieve it, and then you have one way audio?  Quite odd if so....

-Chak

[tim.miller@tnlottery.com]

That is correct.  When I perform a resource trap on the call I notice after placing a call on hold that a different channel and transmit link is used.

[tim.miller@tnlottery.com]

In the test scenerios we were IP to TDM and TDM to IP only.  It is much more difficult to recreate the voice loss in the IP to IP attempt.

[ralph]

What platform are you running on?
This sounds like either an E2T issue or DSP to me.  Since you've replaced the DSP, I'd lean toward a bad E2T which means replacing the controller.


Ralph

[Chakara]

  How about the logs and alarms on the system - any hints there?

-Chak

[tim.miller@tnlottery.com]

Strange thing is there are no alarms or warnings in the logs regarding DSP, E2T or any other as best as I can determine.  I agree that the E2T may be ready to blow since we have been running on this unit for over 5 years.

[glennmitel]

please make sure CRC4 is enabled this is the biggest cause of this problem

[ralph]

I admit to being clueless here:  What is CRC4?

Ralph

[glennmitel]

hello ralph

have a look at this

http://en.wikipedia.org/wiki/Cyclic_redundancy_check

[ralph]

Ah!
So continuing on the ignorance train, where is CRC4 enabled?   Data switches?

Ralph