is it over MRA or internally ?
if MRA take logs from Expressway and both Jabber Run it on CSA Tool. You will get more information about what happens with the phone service. What about your expressway certificates ? is it asper the requirement. What type of deployment is this dual nic or single nic? dual domain or single domain ?
if Internally not working, take logs from Jabber and use it on CSA tool.
You can access the CSA tool from below link.
