Location, location, location
The Federal Communications Commission was directed by the Wireless Communications and Public Safety Act of 1999 (the "911 Act") to require the capacity for mobile phone tracking when dialing 911. I suppose if I drive off an embankment there's some comfort to be had knowing my carrier could compare the time delay of my GSM phone's signal between towers to determine my location.
However, outside of domestic emergency calls, the reality of the situation is quite different. My mobile carrier can't seem to tell what country I'm in, or whether I made a phone call at all.
When they're not engaging in security theater, mobile providers may grudgingly admit this. Recently I returned from several trips abroad to find T-Mobile had billed me for numerous calls I hadn't made from my mobile phone. Annoyed at the monthly pileup of erroneous international roaming fees, I naturally protested.
However, I wasn't prepared for a customer service manager to explain that their billing system, into which roaming partners insert data, sometimes drives the call origination record, not the other way around. In other words, when incomplete information showed up in their database indicating a call had been made or received, a guess at the connection and origination data was recorded -- and I would have to produce bills from the landline carrier to prove otherwise.
Missing call records might be understandable if roaming call data wasn't sorted properly between mobile carriers, but false positives in a call database are surprising and disturbing. It turns out that when I used a landline to dial my voicemail, their system simply assumed that I was calling from my mobile phones last known roaming location and billed me accordingly -- even when the phone was powered off.
Arriving back in Seattle, were I to call the voicemail system from my home landline before turning my phone back on, it would report that Id made a call to the US from the Middle East on my mobile. Given that I'd previously been traveling in an area of interest to the US intelligence community, this means that all of my thrilling calls to voicemail -- from a US-based trunk line to a US-based voicemail system -- were likely recorded for some poor GS-5 to review for clues about Osama's location.
So much for Reiser pulling the battery out of his phone to (allegedly) evade tracking. Apparently some phone companies will continue to report an assumed location to law enforcement instead of admitting they don't have data.
No confidence
While encryption of GSM calls may have been cracked (again) recently, the confidentiality of mobile calls has always been weak. There's more to worry about in the integrity of the data on the phone company's side, and many telecommunication companies don't have a good record either of managing their own call data well, or of shielding it from unauthorized viewing and possible modification.