Yes, he kept the number and transfered the sim card to his new phone.
Great idea, we haven't thought about this. Will let him know to put the sim card back in the old phone and see if it helps, I guess it's very possible the Coinbase Wallet app is checking if the sim card is inside and if not fail to authenticate.
Surprises my why a non-custodial wallet would first have to check for a phone number for authentication, but then again, I am not surprised. Even Coinbase non-custodial wallet collects lots of personal data from a user's device as far as I understand
Keep us updated.
Unfortunately it didn't work
Even with a SIM card we get the same error. Tried going back and forth with coinbase support but they were not able to help, their support is awful.
Only thing left is to extract the private key somehow, but without starting the app it will be difficult. Device is also not rooted, so backing up App Data without root will be hard. I could try Helium Backup over adb and try to backup the app data of Coinbase Wallet and restore on his new phone, but I doubt it will work.