

What iPhone needs: Core Location Daemon - IdeaExcursion
http://www.ideaexcursion.com/2009/03/11/what-iphone-needs-core-location-daemon/

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jws
Using the GPS would impact the battery life.

I can't say about the cell tower triangulation. Presumably the phone could
send its list of nearby towers and has to keep that list updated anyway to
stay connected, so that should be a minimal effect.

The next question is why only iPhones? Presumably the cell operating companies
have the same information from their end of the connection and could make it
available for any phone number on request without any impact on your battery
life. Of course being phone companies it would cost $5/mo to keep 3 services
informed and if you informed a 4th then it would be $0.25/update for a $1800
overage charge.

