Abstract: A peer to peer messaging protocol allows for messaging using a variety of media and for changing the media during a messaging session. The protocol requires far less code space to implement over existing messaging protocols, such as session initiation protocol, and real time transport protocol. The protocol employs a capability exchange (602) for establishing the media capabilities of the respective peer devices as both a request and the final negotiation. The capability exchange messages use a common header (103) that is also used in subsequent data transmissions carrying the actual message content.