1.7 Versioning and Capability Negotiation
This protocol has the following versioning and capability negotiation constraints:
Supported Transports: RTP is transport-agnostic and can be implemented over any connectionless or connection-oriented transport protocol. UDP is the most common transport protocol and is the only transport protocol specified in this document.
Protocol Versions: The version of the RTP protocol is explicitly indicated on the V field of every RTP packet. Only version 2 of the RTP protocol is specified in this document.
Capability Negotiation: Capability negotiation is done by non-RTP means, usually through a higher-level application layer protocol such as SIP, H.323, and SDP.