"With a landline, by contrast, the most that can be determined is whether or
not you have taken any calls placed through, and whether or not you placed
any calls"
Actually, the only thing that can be determined by default is whose name the
landline is registered in, and that *someone* received a call on that
landline, and from what phone number, or that *someone* made a call from that
landline, and the number called (unless there is a human listening in who
knows your voice, or a *very* impressive voice-recognition algorithm). Of
course police and other state agencies have long-standing powers to tap
people's phones, record their conversations, and so on, and in many countries
(including mine) these powers have recently been significantly expanded to
allow state agents to tap directly into telecoms systems, and monitor
people's call without reasonable suspicion ('probably cause' in legal jargon)
or a warrant.
I agree though that using a cell phone adds to your attack surface, and using
a handheld computer as a cell phone adds significantly more, and that we're
only just beginning to figure out how to mitigate this. Ultimately it comes
down to a cost/benefit analysis; do the benefits you gain from using a cell
phone (or a "smartphone") outweigh the costs of making it much easier to
track and spy on you?
I do currently use an old school dumbphone for voice calls and texts (SMS),
but I treat it as the tracking device it is, and turn it off or leave it
behind as appropriate (although this too has some risk of attracting unwanted
attention just as using PGP for email does). I have a couple of second-hand
Android devices, which are useful for quick net tasks while traveling like
checking directions or finding a cafe that serves vegan food, but I only turn
them on when I need them, and I don't usually put a SIM card in them.
