rtp8000Imagine an offer SDP that has one of m with codecs 8 and 101 for DMTF and marked as sendrecv: m = audio 35904 RTPAVP 8 101 a = rtpmap:8 PCMA8000RTP opens two ports for communication. One for the media stream (an even port number) and one for control (QoS feedback and media control) - RTCP.