RTP opens two ports for communication. One for the media stream (an even port number) and one for control (QoS feedback and media control) - RTCP. The port numbers are not hard defined, it depends very much upon the application.

H.261 is an ITU-T video compression standard, first ratified in November 1988. It is the first member of the H.26x family of video coding standards in the domain of the ITU-T Study Group 16 Video Coding Experts Group (VCEG, then Specialists Group on Coding for Visual Telephony). It was the first video coding standard that was useful in practical terms.

This SonicWALL signature identifies legitimate Real-Time Protocol (RTP) with Encoded Payload traffic over UDP.