There are also standalone Meshtastic devices that don’t require your phone as a medium, but obviously they’re far less intuitive than an app.
Would it be still too risky to take an old phone that no longer has a SIM, running a custom ROM, and only tethered to one of these? Or would the Bluetooth still be too traceable?
No SIM wouldn’t really make any difference, all (US) phones must be able to make a 911 call even if they aren’t currently in service (that’s what SOS in the signal meter means too, you aren’t roaming or don’t have roaming turned on but the rival carrier’s tower that you are hitting legally must allow you to make a 911 call). Just because your carrier doesn’t support those frequencies anymore doesn’t mean there aren’t other carriers that do or that the mobile cell tower spoofers won’t still scan for those frequencies. If you trust that it will stay in airplane mode and that the custom rom’s Bluetooth stack is locked down enough to not ping any Find My devices or similar then maybe but standalone Meshtastic device sounds like the best bet to me, or maybe something like IP over HAM radio. Maybe it’s time to dust off the Cybiko!!!
There are also standalone Meshtastic devices that don’t require your phone as a medium, but obviously they’re far less intuitive than an app.
Would it be still too risky to take an old phone that no longer has a SIM, running a custom ROM, and only tethered to one of these? Or would the Bluetooth still be too traceable?
No SIM wouldn’t really make any difference, all (US) phones must be able to make a 911 call even if they aren’t currently in service (that’s what SOS in the signal meter means too, you aren’t roaming or don’t have roaming turned on but the rival carrier’s tower that you are hitting legally must allow you to make a 911 call). Just because your carrier doesn’t support those frequencies anymore doesn’t mean there aren’t other carriers that do or that the mobile cell tower spoofers won’t still scan for those frequencies. If you trust that it will stay in airplane mode and that the custom rom’s Bluetooth stack is locked down enough to not ping any Find My devices or similar then maybe but standalone Meshtastic device sounds like the best bet to me, or maybe something like IP over HAM radio. Maybe it’s time to dust off the Cybiko!!!