Originally Posted by
BigFlyer
This sounds potentially dangerous - if the phone switches networks to the one with service, then you are paying for roaming.
An alternative way of doing this:
- Unconditionally call forward the US AT&T number to a Google Voice number.
- Install GV app on your phone.
Once you've accomplished that (assuming you have data from an esim) you have free incoming calls to your AT&T number (forwarded to the Google Voice app), and free outgoing calls through Google Voice. If you want to call people stateside with your normal caller ID showing, Skype can be set up to show your regular phone's caller ID for outgoing calls.
I may not have explained this very well, but I'm not sure what you are referring to when you said "The One With Service". That service is On by design. It is there to provide data for the non carrier voice line as a WiFi substitute. That line line with Network Selection switched Off, won't spontaneously turn On and begin roaming unless you do a Network Reset. Even then, I am on T-Mobile and that line gets free roaming anyway, so I wouldn't be charged.
I have done this literally dozens of times and it has never switched independently. I see no risk in this setup with the configuration I have detailed. On an iPhone you have a continuously visible indicator in the status bar that your voice line has no bars/no service. This seems no more likely than your phone switching from Google Fi to AT&T or Verizon. I also don't believe text messages call forward, so that would be a disadvantage to me.