Avaya jdrosen.net Skype IBM Presence and Instant Messaging (IM) bridging involves the sharing of presence information and exchange of IM across multiple systems within a single domain. As such, it is a close cousin to presence and IM federation, which involves the sharing of presence and IM across differing domains. Presence and IM bridging can be the result of a multi-vendor network, or a consequence of a large organization that requires partitioning. This document examines different use cases and models for intra-domain presence and IM bridging. It is meant to provide a framework for defining requirements and specifications for presence and IM bridging. The document assumes SIP as the underlying protocl but many of the modles can fit other protocols as well.