How To Use Audio Files With SIPp

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SIPp’s PCAP play feature can replay pre-recorded audio stream towards destination (see [1]). Doc mentions tcpdump and Wireshark as tools to record such RTP streams without further details.

Looking at SIPp 3.2 source archive, I found PCAP samples in a pcap/
directory. Sample pcap/g711a.pcap file includes RTP from to

1. How can you “forge” IPs and/or ports of a pcap file ?

2. When generating simultaneous calls from one source device to a single target device, do you need to have specific PCAP files (one specific for each call) with specific source port ?

3. How do you capture an RTP flux with thark or tcpdump ?

Best regards


4 thoughts on - How To Use Audio Files With SIPp

  • You don’t have to. sipp only takes the rtp payload from the packets in the pcap then just sends the datagrams to the remote in the scenario.

    Nope. See above.

    This is a little tricky. tcpdump isn’t much help if you don’t know the ports. With tshark though you can create a “read” filter that can capture only RTP packets but it’s very expensive. Usually, I just capture all UDP
    packets between the hosts in question with tcpdump, then use the Wireshark gui to filter the rtp stream. Then you can just export those packets.

  • Thank you very much George for replying.

    2018-02-09 14:39 GMT+01:00 George Joseph :

    That is exactly what I’m after !

    Before diving into this, can I ask which SIPp version and feature are we talking about here ?

    Since I posted my question, I’ve read this [1] thread mentionning a new WAV
    file playing capability but this feature required SIPp 3.4 and above. On Debian Stetch I’m playing with, packaged SIPp is 3.2.


  • We’re on 3.5.

    That’s pretty old. I’d recommend compiling from source yourself. It’s very easy to build.