It may be possible to remotely turn the phone on via the modem. However, if
the modem is actually in an off-state (which is what I'm talking about) it
shouldn't be possible to turn on remotely.
If the modem is on I'd agree with you in that it can access CPU, memory, etc
most likely. From what I have read though it appears to differ from phone to
phone and there is a possibility that with the right phone it may be possible
to prevent a phone's modem from accessing the memory / CPU.
I have inquired before and been told it isn't possible to do what I'm
imagining. However I believe that was a slightly different idea in that you
would have a one-way receiver to inform you of incoming calls at which point
you could connect to the network and pick up or not. I realize that idea
would have required a system where there was a server which took the actual
call, told the person on the other end that the person was trying to be
reached, and then have had the cellular user receive a one way page, with the
question “should I connect to the network, (would then identify ones
location), and then dial the phone number of the server”. That appears to
not be feasible because of the way all technology works. There is no such
thing as a one-way receiver. Apparently pagers were always two way
technically or the ones which were no longer work (since the move to
digital).
However I'm not firmly convinced something couldn't be done. I suspect it may
simply require a lot more investigation and time and somebody whom truly
understands what the objectives are.
The objective are not to eliminate the ability of providers to track users at
all. The goal is to make detailed tracking much more difficult.
If the on/off thing is possible and the separation of CPU/memory from the
modem's memory/CPU then you could possibly prevent the modem from spying on
the user. You'd still be locatable at any point in which the modem was on.
However if you only turn the modem on at certain intervals and pull email it
would not be possible to get a detailed map of the location of an individual
unless it was constantly being turned on/off (defeating the purpose). However
you could simply use the device over wireless first, and then via a GSM
modem, and if the phone is not attached to you, via Tor, thus preventing the
phone company from knowing who you are. They would only know where you are
when you allow them to discover your location. So ideally you would never
check your mail from the same place twice. And such a system would not work
well (or at all) with voice. Well, it might, but that would be a lot
trickier. It would probably require a custom version of Tor that had its own
high speed onion network that was run off only high speed nodes.
