Handling media with SIPp

SIPp is originally a signalling plane traffic generator. There is a limited support of media plane (RTP).

RTP echo

The “RTP echo” feature allows SIPp to listen to one or two local IP address and port (specified using -mi and -mp command line parameters) for RTP media. Everything that is received on this address/port is echoed back to the sender.

RTP/UDP packets coming on this port + 2 are also echoed to their sender (used for sound and video echo).

RTP streaming

SIPp can play a PCMA, PCMU, G722, iLBC or G729-encoded audio file over RTP.

More details on how to do this can be found in the action reference section.


The PCAP play feature makes use of the PCAP library to replay pre- recorded RTP streams towards a destination. RTP streams can be recorded by tools like Wireshark or tcpdump. This allows you to:

  • Play any RTP stream (voice, video, voice+video, out of band DTMFs/RFC 2833, T38 fax, …)
  • Use any codec as the codec is not handled by SIPp
  • Emulate precisely the behavior of any SIP equipment as the pcap play will try to replay the RTP stream as it was recorded (limited to the performances of the system).
  • Reproduce exactly what has been captured using an IP sniffer like Wireshark.

A good example is the UAC with media (uac_pcap) embedded scenario.

SIPp comes with a G711 alaw pre-recorded pcap file and out of band (RFC 2833) DTMFs in the pcap/ directory.


The PCAP play feature uses pthread_setschedparam calls from pthread library. Depending on the system settings, you might need to be root to allow this. Please check “man 3 pthread_setschedparam” man page for details

More details on the possible PCAP play actions can be found in the action reference section.