Cannot sign in with AppleID because iPhone is carrier-locked 'SIM not supported' - won't receive codes.

"If your iPhone can't be activated or an alert says the activation server is unavailable or the SIM card is unsupported," click here and read the document 'If you can't activate your iPhone' --> https://support.apple.com/HT201407

I am would think can sign in without having to receive a SMS. I do not have a phone capable of SMS. Set up alternative trusted devices.

To see how to 'Get a verification code and sign in with two-factor authentication', click here --> https://support.apple.com/HT204974 - "Whenever you sign in with your Apple ID on a new device or browser, you'll confirm your identity with your password plus a six-digit verification code. There are a few ways you can get a verification code. You can use the code displayed on your trusted device, get a text or phone call, or generate a code from your trusted device." Instructions at the end about what to do if you don't have any other trusted devices and need to use account recovery.

Incidentally I would definitely set up other trusted devices other than the phone. If the phone is lost or damaged she won't be able to get a code on it for her replacement phone. You'll be back in Catch-22.

You're welcome!