...
If the call fails, first check that the PrivateGSM configurations are correct and if not, fix them and close the Incident else . If they are fine, let's (DRAFT) User can't call - professional to the second level
If PrivateGSM reconnects to perform the test call, then most probably we had a Temporary Network Problem issue. Let's check if the User can call other party now, if he (she) can then close the incident. If the User still can't call then check that the other device is connected and registered and if it doesn't, close the incident as "Not an issue".
If the other party is connected and registered then escalate to the second level.
Second Level Anchor escalate escalate
We can receive an escalation request either for a User's remote party configuration check or for a PrivateServer status check.
...