You may test your 911 information by dialing 933 on your voip phone. This should tell you the address and callback number associated with your voip number. It may also tell you which Public Safety Answering Point (PSAP) your call will be routed to.

If you test the 911 information by dialing 933 and you get this message:
"Please wait while we try to locate your party or press 1 to leave a message."
This indicates the service is functioning.
I assume this is a voip.com specific feature - it does not appear to be generic.