In my area, the local PD does NOT handle 911 calls--there is a county-wide dispatch office. Not knowing that at the time, I called the local PD, and they gave me the number to dial.

When I called to inquire, the person answering the phone said, "911, can you please state the nature and location of your emergency?" Turns out the 'back line' for our PSAP (dispatch) is the same as the 10-digit non-emergency-trunk number. (ie. the number you'd set to dial 911 from your ATA's dial plan if your provider doesn't offer 911 service) When I told them why I was calling, they acted as if they got this type of request all the time and that calling back via 911 was OK at that time. Called, and it worked fine, both with Voipo and CallVantage.