I am not sure if you have rebooted your CUCM server but that is a step that seems to be needed under the Administrative guide and configuration steps. Please refer to step 3, section i as stated in - http://www.cisco.com/en/US/docs/voice_ip_comm/jabber/iPad/Admin_doc/output/b_Jabber_for_iPad_admin_guide_chapter_010.html#task_15D8898B81DF484EAF66ADBD27CA2C11
Hopefully, this helps you. If not, I am not sure what your issue may be. I recently configured the same on a CUCM 7.1.5 system, but have not rebooted my cluster yet, and can't make calls.
Thanks, Arras
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