Accessing networked appliances using the session initiation protocol

This document proposes the use of session initiation protocol (SIP) for network-capable appliances. It leverages standard SIP capabilities to directly communicate with appliances even when they are behind firewalls, network address translators (NATs) or other entities that prevent direct end-to-end communication. When combined with the recently proposed instant messaging and presence SIP extensions these techniques become even more powerful to allow the secure and reliable access to appliances in a variety of different networked environments