This document defines an alternative connection model for MSRP UAs. The model differs from the standard MSRP model, as defined in RFC4975 and RFC4976 in the following ways: it uses COMEDIA for TCP connection establishment, and it allows the usage of SDP in a more conventional way for conveying endpoint address information. Because of this, the model also allows for the usage of generic mainstream mechanisms for NAT traversal, instead of using MSRP relays.