none of your CTI devices seem to be registered. Check the status on call manager once. If not registered then, you need to get them registered first. check TSP config on the CUAC server. -Atul

The error states the server cannot be contacted.  Probably you can try testing by installing the client on the CUAC server itself. -Atul

If it works on phones registered to publisher but not the ones registered on subscriber, I would check for dbreplication issues.  https://supportforums.cisco.com/document/52421/troubleshooting-cucm-database-replication-linux-appliance-model Regards, ...

Try escape character '\' before the space, if that doesn't work you'll have to go to TAC for deleting it via root access. 8.6.2 does give you an error if the file name has spaces. -Atul

As per the debugs, the INVITE is sent out to the ISP, but we don't get any response from them. -Atul