Introduction
This is one of the most claimed incidents to occur. This Incident troubleshooting must be confronted only if the incident definition and description hasn't pointed out any operational requirements violation. "User can't call" cause is equally divided into client/server misconfigurations and connection issues.
SrvRspWarning
Please keep in mind that a call can fail due a reason that doesn't depends on the client (e.g. License problems, user offline or doesn't exist, etc...). In these cases an error message should appear on the client screen, so check any message before to proceed to troubleshoot an incident of this kind.
See TODO: insert section
