SMS-based two-factor authentication (2FA) has been declared insecure and soon it might be a thing of the past. NIST has released a draft of its Digital Authentication Guideline that says SMS based 2FA should be banned in future due to security concerns. The DAG draft notes that 2FA via a secure app or biometrics, like a fingerprint scanner, may still be used to secure your accounts. Many tech companies such as Facebook and Google offer in-app code generator as an alternative solution for 2FA.
Source: https://thehackernews.com/2016/07/two-factor-authentication.html