In computer networking, the Message Session Relay Protocol (MSRP) is a protocol for transmitting a series of related instant messages in the context of a communications session. An application instantiates the session with the Session Description Protocol (SDP) over Session Initiation Protocol (SIP) or other rendezvous methods.
The MSRP protocol is defined in RFC 4975.[1] MSRP messages can also be transmitted by using intermediaries peers, by using the relay extensions defined in RFC 4976.[2]
MSRP is used in the RCS context, especially for the instant messaging, file transfer and photo sharing features.