Happened to me twice, with sufficient time between the incidents that I had forgotten about the first block when I encountered the second one - so in both cases I spent more than an hour trying to figure thinhgs out.
I don’t think that email is the appropriate communication channel when someone tries to use the phone system. Insterd, the system should provide an error message that gives the user enough of a hint about where to look for a solution
I previously have complained here about misleading or uninformative error messages:
My challenge to the good folks at VOIP.MS is this: you are communication specialists - can you please ensure your technology communicates well with us users? 
Many thanks!
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