Select "Try another way" during sign-in to use a recovery phone number instead . Recovery Failures
Depending on how you set up your security, here is how to retrieve your code:
When you try to sign in to your Gmail account from an unfamiliar device or location, you'll be prompted to enter a 6-digit verification code. Here's what you need to do:
Sometimes SMS messages are delayed. Wait 5-10 minutes before requesting a new code [1].
A message sent to a secondary email address you previously linked to the account.
If you lose your SIM card abroad, you lose SMS 6 digit codes. Add Google Authenticator (which works offline) before your trip.