I have had the same problem and have just managed to resolve the problem. We are running Jabber 10.5.1 on Android kernel 4.2.2.
Jabber on Android cannot support HOSTNAME with the Android kernel less than 4.4.4, and therefore Jabber cannot connect to Call Manager.
You can correct the issue in one of two ways:
1. Change the hostname of the CUCM servers to the FQDN or IP address
2. Add the "Organization Top Level Domain" (CUCM system => Enterprise Parameters) as "cisco.com" for instance, then Jabber will do DNS query with "<servername>.cisco.com"
I just implemented option 2 and this resolved the problem. This was also a non-impacting change.
I hope this helps. Best of luck.
I went to CUCM System-->Enterprise Parameters but I can't find a way to add "Organization Top Level Domain". Can you point me to the right direction?