Support CISCOVTGTOKEN beside PLAIN for XMPP Client Authentication Sequence.
given <mechanism>PLAIN</mechanism>
requested <mechanism>CISCOVTGTOKEN</mechanism>
Cisco describes the Authentication Sequence in document "Developer Guide for Cisco Unified CM IM and Presence Release 10.5" page 10.
https://developer.cisco.com/fileMedia/download/a2ce9071-4c3b-4ad5-adaa-095153ea1b4c#page=10

This would be a small extension that opens up into a larger community of users.