For desktop share BFCP is used, make sure the SIP profile that is assigned to the DX650 has BFCP. I dont have a UCM in front of me right this second, but there might be a checkbox to check "Enable BFCP" right under the DX650 phone configuration in CUCM. This depends on the version of UCM. Also, the CSF for the windows client also needs BFCP enabled either under SIP profile or the device itself. Keep in mind that Jabber client needs to be on a softphone call to be able to share the desktop.
Windows Phone dont support Jabber.
Android based devices support Jabber but only a few of them. If you cant find the app in the play store from your device, then its not supported. However you can download the APK file from Cisco.com and install it. Its "supposed" to work but thats something you will have to try.
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