Smart Phone Recommendations, Please
This actually sounds like a feasible idea- with a data adapter of some sort, it seems like it could be possible to use it as a 'phone' when necessary.
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.