Can you look at your expressway-E for logs associated with your phones public IP.....
Last time I had one of these questions it was that the device was not build or associated with users correctly.
Do you see any error messages on the logs?
I reached to the cisco sip proxy feature service is not running and I tried to run it but no way
and the error displayed on mopile in attach
Please try to reset jabber in mobile once and if you still have issue then share Jabber problem report from mobile here to check the issue.