Hmmmmm,

Strange as it may seem, but I believe that we actually agree?

1. Your "multilateration" is what I would describe as multiple or cross triangulation? Please be aware that I do not use your terminology........... I date back to chucking 105mm pills 11,000 yards or so........

2.
there absolutely is a circular area of probability the location systems determine someone to be within. However, you are inferring the concept of it only measuring an area around a single BTS
Bad expression on my part old chap!.............. my point was that you needed the initial point of contact as a reference? That will be the tower that the cell is using.

3.
are you suggesting that these phones are constantly calculating and uploading their current location to a system within the carrier?
Absolutely not! this is a service that you have to request or initiate. Your emergency call example is a case where this happens automatically? You need the capability, then you need to start it off?

4.
this is completely false. location services work just as well for prepaid phones as they do post paid. statements to the contrary are simply ridiculous and would suggest that E911 services would not work for people using prepaid phones (which hopefully everyone here knows isn't true)
Of course they do. I am going back to the fact that the original poster is a Bounty Hunter. You can tell me that a cellphone has dialled 911, and you can tell me approximately where it is located. YOU CANNOT TELL ME WHO DIALLED 911

Our Bounty Hunter is very interested in the "who" bit?