Scaling Optimizations for Presence in SIP/SIMPLE

The document suggests various optimizations for presence that uses the SIP/SIMPLE protocol. The suggestions are based on a separate document that contains scaling analysis and requirements. The current document reviews only suggestions that are not yet part of the work of the various SIP working groups while approved and in-work optimizations are reviewed in the scaling document. The intention here is to keep these suggestions at this document as a place holder until a set of requirements will be discussed and accepted and the work on optimizations will commence.