On Feb 6, 2010, at 8:16 AM, George N. White III wrote:

> On Fri, Feb 5, 2010 at 4:12 PM, Neil Laubenthal <[email protected]> wrote:
>> I don't know for sure . . .but would imagine that one of the things that the 
>> cell tower transmits is some sort of location information.
>> 
>> 
>> On Feb 5, 2010, at 12:38 PM, Chad Leigh -- ObjectWerks Inc wrote:
>> 
>>> Honest question here:
>>> 
>>> How can it uses the cell towers to figure things out if there is no data 
>>> plan to ask someone?  Does it have a list of all cell towers in it 
>>> somewhere?    I would think that it would need to communicate with someone 
>>> about it after getting tower info from the towers
>>> 
> 
> The law in US and Canada says you can always use a cell phone for 911
> calls even without a plan.  One of the reasons for GPS in cell phones
> (besides helping the men in black track the locations of "persons of
> interest") is the problems that have occurred with 911 calls ended up
> on a tower  in a different jurisdiction where the 911 call center
> wasn't familiar with the place names used by the caller. This often
> happens on shores of places like Puget Sound and the Bay of Fundy
> where different jursidictions are separated by bodies of water narrow
> enough that cell signals can reach towers serving the opposite shore.


Yes, but this has nothing to do with the question.  I am not asking about using 
a phone to make a call like 911 even without a plan.  I am asking how the phone 
can use the cell towers to assist the GPS without a data plan to get cell tower 
info from a database somewhere or something.  Using the phone without a plan 
for voice is an easy proposition.

Jared sent a wikipedia link about assisted GPS.  At least one of the methods 
there relies on an IP link so that a central server can be accessed.   Again, 
without the plan, how does it get access to the IP network?  I did not 
understand most of the stuff on the wikipedia link on assisted GPS I will admit.

Chad

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