This does work at the moment, that's why I said what I said (atleast on Pixel w/ Android 10) and you're supposed to use residential IP, I thought these were understood, sorry for the confusion.
Like @pillaicha said it does work on airplane mode for a short while, long enough for you send sms, call and whatever else you want to do.
Edit: If you're doing this on android, by default if latency is higher than certain ms it won't even try but you can change this while building your system image or if have write permission on / I guess.