The Session Initiation Protocol Project INvestiGation (SIPPING) working group is chartered to document the use of SIP for several applications related to telephony and multimedia, and to develop requirements for extensions to SIP needed for those applications. Such requirements will be referred to the SIP working group for development of any new SIP method, header, or option-tag as described in Change Policy for SIP (RFC 3467). Guiding principles for the performance of SIPPING's work will include: 1. Documenting the requirements of specific chartered tasks. 2. Documenting the usage of SIP to solve real problems that need to be solved in a standardized way. Examples of important topics identified are the session policy architecture, allowing network entities to convey policy into an User Agent's activity; requirements analysis for session border controllers to determine how best such devices can operate with SIP usage; guidance on IPv4-IPv6 co-existence support by SIP and SIP-supported media; and inclusion of real-time text conversation (ToIP), service invocations benefitting hearing and speech impaired users, and other SIP equal access services as requirements are proposed. 3. Looking for commonalities among the chartered tasks and ongoing SIP-related development, as commonalities may indicate for general, reusable functionality in SIP. 4. Describing the requirements for any extension determined to pass there hurdles, and handing the development task to the SIP WG. 5. Developing procedures and requirements for configuration and delivery of SIP User Profiles Besides performing needed specification of several applications of SIP, SIPPING can be seen as also working out use cases that clarify the role of SIP in the Internet, and help to ensure that Occam's razor is appropriately applied to SIP usage. The security of all the deliverables will be of special importance. The technology for security will be keyed from the SIP Security specification within RFC 3261, and additional SIP specifications as they apply.