I keep wondering about the phone mast times too. How certain are we that they are correct times and not out by an hour (for example)?
Do the clocks change in Portugal or in phone mast analysis countries? I am only wondering; it is not that I think anything is wrong.
The hour is very exact and it's given by operator. Of course it's local time unless it has some label like GMT or UTC. These days they usually must have a source of time ordered by law. This is not recent, but I can't be sure it was so in 2007. Anyway, any source they use won't be more than 1min. away from a reliable source under any circumstances. Problem is location. There's no such thing as OC's mast. There's a mast in PDL and it covers a wide area. A call using that mast can be anywhere within coverage area and there's no way to tell how distant from mast or which direction from it.