CHANNEL_SPECIFIC_HANDLES

The members of this group have handles which are specific to this channel, and are not valid as general-purpose handles on the connection.

Depending on the channel, it may be possible to check the HandleOwners property or call GetHandleOwners to find the owners of these handles, which should be done if you wish to (e.g.) subscribe to the contact's presence. Connection managers must ensure that any given handle is not simultaneously a general-purpose handle and a channel-specific handle.