Regarding the comment about "them" not liking it if you test your 911 service...
No they won't.
Yes, they will. Your answer doesn't dispute that. You are simply telling people that certain ITSPs supply a special 933 test number. That number provides a test from your device to the company that provides the 911 interconnection, to confirm that a) it works, and b) they have the correct street address that you entered. Calling 933 is not going to the actual PSAP (emergency call center), so there is no problem testing the service by calling 933. There IS a problem testing by calling 911. That was the question being asked and answered.