I'm sorry about the issue. Please try the following fix:
- On both iPhones, Settings app icon, then tap on option FaceTime (scroll down as needed), then turn OFF the option iPhone Cellular Calls.
- On both iPhones, open Settings app icon, then open the option Phone (scroll down as needed), then turn OFF the option All Calls on Other Devices.
- If that still does not work, if you and your wife use the same Apple ID account (using the same email address for Apple ID account), then create a new Apple ID account at the website below:
, then do the following on one iPhone only:
- Open Settings app icon, then open option iTunes & App Stores (scroll down as needed)
, then tap on the current Apple ID / email address
, then tap on Sign out
, then sign in with the new Apple ID account you've just created.
Please reply at the box below to continue troubleshooting. Thank you.