To answer the question about what number is shown at the PSAP. I would have to say it depends on what the PSAP is capable of receiving. Now, before you say that is a cop-out, in this city all cellular calls come in on dedicated trunk groups. So immediately the operator knows it is a cellular call. The location given, and this is from memory from working with it a couple of years ago is that of the cell tower. As far as locating a cell phone from a cell tower, it takes a while but it can be done through triangulation. One has to assume the signal is being seen by multiple towers, but the tower having the best reception will be the primary tower for handling the call.
As far as GSM, or CDMA or IDEN transmitting your location by using GPS, this is possible. But not all phones are GPS enabled nor have all cellular carriers upgraded all their equipment to handle reporting of GPS data and not all PSAPs have been upgraded to receive the data. This is a technology that is very much in progress and is being deployed. The deployment isn't as quick as some would like, but it is being rolled out. In fact I am currently testing one of the latest converged devices from a major manufacturer and it is not GPS enabled even though it was released within the past 90 days.
Yes, the issue with getting 911 turned on with VOIP, whether it be Vonage or one of the other carriers is something that has to be worked out. With your statement above you are beginning to see some of the technical issues with attempting to tie everything back to a telephone number. If you take your Vonage adapter and a telephone from Independence to Tulsa and make a 9-1-1 call, what PSAP is going to get the call? From the description you have provided it will be the one tied to the location information given when you enabled the service. This isn't much help in Tulsa. If you had the boundary router or some other device route the call based on where it was first received, how would you track it back to the physical location? Unlike a cell phone you aren't hitting different points with different signal strengths that can be triangulated, and the last time I checked, GPS doesn't work indoors.
While Independence handles 1 or 2 emergency calls per day, this city handles between 20 and 40 an hour with more, up to 200, during peak periods. This includes the true emergencies where a police or fire & EMS response is needed to the calls about potholes, trash, illegally parked cars, and time-of-day requests. With 20 operators on duty and over 100 calls in an hour means a call is coming in about every 100 seconds. Now, add a mix of numbers coming in on the administrative lines, like 3-1-1, and you have a good chance the emergency on the non-emergency line is not going to be answered, sometimes for several minutes. You can imagine the hew and cry that would be raised because their emergency, however legitimate, wasn't answered immediately.
Now to give you an idea of call flow, the call is taken by a trained operator. The operator asks the diagnostic questions to determine the type of emergency, takes necessary data to fill in the Computer Aided Dispatch (CAD) entries and the computer sends the call to the appropriate dispatcher. The dispatcher, based on the CAD data selects the closest unit for response and assigns the call a priority. If the call is for medical services or the fire department, once the call data is logged it is transferred to Fire / EMS for dispatch. The call taker remains on the line to be certain a police response is not required before disconnecting (like an auto accident with injuries). If police response is also required, the CAD data is then sent to the police dispatcher for action as well. If police response is not required the call taker is then available to take the next call in queue, 9-1-1 calls first.
While it is the responsibility of the government to protect its citizens and visitors, the costs of the equipment and personnel handling emergency calls are _partially_ offset by the fees collected. This is where the VOIP callers end up on the wrong queue. As they refuse to collect and pay the fees, their calls are not priority but administrative.
Rodgers Platt