For file-based installations, Message Queue 4.3 is co-packaged with Communications Server. For UNIX package-based installations, Message Queue 4.1.1, which is functionally equivalent to 4.3, is provided. Despite the version numbering, Message Queue 4.1.1 is actually backward-compatible with Message Queue 4.2.
The embedded Sun GlassFish Message Queue code that is supplied as part of Communications Server is only tested and certified (typically) against the equivalent version of the Message Queue broker. This means that using the supplied embedded Message Queue code to connect to a remote (not managed by Communications Server) Message Queue broker running a different version of the Message Queue code is not supported.