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How to identify, which codec is used in VOIP rtp packets ?


In this pcap file, I can find RTP, RTCP, and STUN packets. I tried to check which packet does negotiate for the codec, but couldnt find it. Can you please share any idea, where should I look to find this negotiation ?


asked 09 May '15, 09:08

Shas's gravatar image

accept rate: 0%

One Answer:


Some observations here:

  • I see some encrypted TCP communications
  • Of the so-called RTP/RTCP packets, most make no real sense (probably trapped by 'try to dissect outside conversation')

This leads me to believe that the UDP packets also contain some form of encrypted communication, which could be the VoIP packets you are looking for, but which won't reveil there contents.

answered 09 May '15, 10:13

Jaap's gravatar image

Jaap ♦
accept rate: 14%