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Art wrote:
> gabriel rosenkoetter wrote:
> >I'd hazard a guess that a cell phone without active service doesn't
> >have a subscriber entry anywhere which means that the 911 systems
> >don't have a provider interface from which to get the calling cell.
> >(Remember that the call comes through just like any other phone
> >call; the information about calling cell isn't in some carrier
> >signal, it's based on the CID information--or, actually, probably
> >the ANI information. I've only a peripheral knowledge of how cell
> >routing works.)
> >
> >
> >
> I don't know enough about it either; just enough to make dangerous
> presumptions. But I always envisioned that the routing system knew what
> antenna/tower received the initial signal and that the routing was based
> on the antenna location without regard to any subscriber info. I would
> really be interested in a definitive answer on this, as it greatly
> affects the value of those donated phones used for 911.
Maybe Magnus will jump in, as TruePosition is working on cell phone
location techniques for just these purposes. Although maybe he doesn't
have heavy involvement in the engineering side. While there has been
talk of GPS 'chips' in cell phones for years, one of the other
techniques of phone locating involves using basic RDF (Radio Direction
Finding) between the tower or towers and your cell phone. This doesn't
require satellite view to make work, and can theoretically be done
cheaper than putting GPS in all the phones. Last I heard, TruePosition
didn't have it fully commercialized, although that could have changed in
the recent couple months.
--
Kevin
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