badtzmaru - 6:23 pm on May 13, 2005 (gmt 0)
Look at Phase 2 E911 deployment at the FCC's website at [fcc.gov...] (I'm guessing links to govt sites are OK). Although the position of the handheld can be calculated via tower triangulation, every handheld shipped for probably the last 24 months has a GPS receiver in it. When 911 is dialed, the phone sends position information to the mobile carrier. The phones typically let you configure whether it is sent with every call or just with 911 calls. If it's sent with every call, it can be used for geolocation services.