Sounds more like a firewall issue.
I would assume that if the port definition is missing the default ports would be used.
Could you tell us a bit more about the deployment, VCS-C or VCS-E used, ice en- or disabled,
what kind of network do you use on the ipad?
I had seen it before some wlan networks do not allow peer2peer traffic within the same wlan,
this would break a non-traversal/local call on a VCS and then sure a firewall is the most likely issue.
In addition, check on the jabber ipad admin guide to see that you provisioned it right.