Not a full guarantee, but removing the battery should also prevent modem
activity.
Some phones have a dedicated battery, but it's the CMOS type (for the
date/time), it should not be capable of keeping the modem on.
But really, even with the Neo900, the only choice is either having a
functional phone (=a phone that can receive calls) and being traced, or
having having a dead piece of plastic/metal and being untraceable.
Bippers could have been a good addition (phone off+bipper on=still can be
reached, without traceability), but the cost is too heavy on the caller, so
it's not worth it.
So it necessarily means that at least from point A to B, your geolocation can
be gathered. but if the phone is unreachable, that gives some geolocation
privacy between A & B.
Personally, while I find it disturbing, trading my geolocation vs having a
functional phone, is kind of OK. If for some reason I need to go undercover,
the phone can simply remain at home, or faraday cage, or removing the battery
etc.
What bothers me much more is the modem isolation. Supposedly good modem
isolation is better than nothing, but it bothers me that it could have access
to the personal data on the phone. Geolocation, on the other hand, I don't
really care.
