In article , Jeff
Liebermann wrote:

There is no way the phone can determine the location of the tower from
the signal,

Sure they can. The signal include Latitude and Longitude for the tower.

My GSM phones show a valid lat-long. My CDMA phones show no data.
This is with multiple phones on AT&T (GSM), T-Mobile (GSM), Verizon
(CDMA) and Sprint (CDMA) in the Monterey Bay area of California. Your
experience may be different in other parts of the country or with
other system operators.

sprint towers include lat/long everywhere i've tried. not all phones
will show it, however.