This memo documents a process intended to organize the future development of the Session Initiation Protocol (SIP) and related work in the Real-time Applications and Infrastructure (RAI) Area. As the environments in which SIP is deployed grow more numerous and diverse, modifying or extending SIP in certain ways may threaten the interoperability and security of the protocol; however, the IETF process must also cater to the realities of existing deployments and serve the needs of the implementers working with SIP. This document therefore defines the functions of two long-lived working groups in the RAI Area that are, respectively, responsible for the maintenance of the core SIP specifications and the development of new efforts to extend and apply work in this space. This document obsoletes RFC 3427. This memo documents an Internet Best Current Practice.