You should use a phone number attached to your FreeTaxUSA account. If you have multiple phone numbers and don't remember which one is attached to your account, you can try multiple phone numbers to find the one that matches your current FreeTaxUSA account.
If you don't have a phone number attached to your FreeTaxUSA account, or if you no longer have access to the phone number on your account, you won't be able to use this method to recover your account. You can still recover your account through email on the
forgot usernameand/or
forgot passwordscreens.