[im3w1l]

To some extent I agree, but if the modem is off how long latency is acceptable for inbound messages? I suppose a low bandwidth broadcast "user 0x76abc937* has a new message" could work. Devices would filter out broadcasts that don't concern them.

* Ideally the user id should be used only once and derived from some pre-shared secret.

[JoshTriplett]

I'm talking about two different cases here.

First, in a case closer to the current world, I'm just suggesting that disabling the cell modem should power it off so it can't do any kind of location or tracking.

Second, in a more ideal world, the concept of "data connection" would be entirely separate from any identity attached to a phone or text message, and you could handle the latter via whatever connection you have, whether a cell data connection or wifi or something else.

[im3w1l]

That makes a lot of sense.