VOIP calls garbled?

I

infamus

Gawd
Joined
Sep 5, 2006
Messages
681
i know this is an issue sometimes. it happened at my last job but i wasnt in charge of fixing it. every so often a call will be dropped or degrade so badly that you cant understand what other person is saying. Specifically with cisco phones. im convinced its bandwidth issues, but it could also be something in the configuration.

it goes like this <phone - nonPOE switch(15thinclients attatched) - adtran 1.5m ethernet handoff - adtran 1.5m handoff at main location-4006 catalyst-CCM server then reverse it if its going from the remote location to a different remote location
 
Sounds like a QoS issue. One way to see and get an idea on jitter and out of sequence that I've used numerous times is a simple Wireshark trace. Get a packet capture of a phone call (port mirror on your switch if you can). Once you have the call and the capture is done go to Statistics --> VoIP-Calls. Click the call and then click Player. In the player click decode. You will see "Drop by Jitter Buff" and "Out of Seq". The nice thing is that you can actually hear the two way audio of the call and see if the audio issues are before or after the phone.

I normally use this more for SIP call flow troubleshooting but it can help give you a general idea...and it's just plain fun/interesting to actually see how the SIP/RTP messages flow.
 
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