Re: Triangulate?
It's part of the protocol for GSM et al. To fit the transmissions from the phone into the timeslot properly, the delay (== distance) to the base station must be known. So as long as the phone sees more than one base station, triangulation is essentially always done. However, the telco may not actually store the data, or keep it around for very long.
Also it's worth pointing out that in the inner city cells are often so small that just knowing which one is the closest is enough to put you within a couple of blocks at most. (And that some telcos leak this info to the whole world over the SS7 network. Wonderful times we live in...)