A good practice in two-factor authentication is to use an authenticator app (like Google Authenticator) as the second factor. Anyway if they haveIf an attacker has access to your phone this won't help you either. But the thing with SMS as a second verification step is that it has severalintroduces additional risks pertaining to carrier security. Due to this, NIST no longer advises to use sms-based 2 factor authentication in the latest sp800-63b publication (https://pages.nist.gov/800-63-3/sp800-63b.html section 5.1.3.2. Out-of-Band Verifiers)