This works on android by registering your application to work correctly with Google's SafetyNet.
Check the documentation on android here: https://firebase.google.com/docs/auth/android/phone-auth#enable-app-verification
There has also been a similar question on how to enable SafetyNet in case you struggle: https://stackoverflow.com/a/64657110/3668241
Maybe also of interest:
For iOS to avoid the verification page, you need to enable silent push notification: https://firebase.google.com/docs/auth/ios/phone-auth#start-receiving-silent-notifications