Subject: Re: OT: Anonymous phone carrier
Furthermore, you can't turn the phone on each time you reach a mile or so away from home, because after a few days/weeks, your path can indicate roughly where "home" is.

That's how the allies located German fuel depots in WW2. The German trucks drove at night with hooded headlight turned on only very briefly. The allies had photo planes in the air, and laid transparent photos taken on different days and different times on top of one another. Soon they could see a solid trail of headlights to the fuel depots.