VoIP UDP codec decoding

Unanswered Question
Sep 25th, 2008

Is there a way to verify the codec that's encapsulated in a udp packet if you are performing a capture on the ingress of a router or switch port?

Thanks,

Brandon

I have this problem too.
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ecarabias Fri, 09/26/2008 - 04:03

You can use the Ethereal or Wireshark applications for decode the RTP packets and see the codec.

philippe.cousineau Tue, 03/30/2010 - 11:38

Wireshark is really nice


Make sure to uncheck the boxes for Enable MAC name resolution and Enable transport name resolution

Aaron Harrison Wed, 03/31/2010 - 01:28

Hi

Well - as suggested the Wireshark community is probably a better place to start...

That said... try:

1) Make sure that you have identified the two streams as RTP. Wireshark doesn't see stuff as RTP initially, so you have to click a packet from each stream direction and set 'Decode As... ' to RTP.

2) When you do Telephone/RTP/Show All Streams you should see a stream for each direction, then click on one and hit analyse...

3) If it won't export 'both' directions, try one direction.. if that works then you haven't marked both streams as RTP, or there's another problem.

Would suggest posting your capture here or at wireshark in that case.

Regards

Aaron

Please rate helpful posts..

philippe.cousineau Wed, 03/31/2010 - 06:02

to fix my problem,

i had to Make sure to uncheck the boxes for Enable MAC name resolution and Enable transport name resolution.

without that I was not able to save the payload to an audio file

thanks

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