MFA Methods Compared: Text Codes, Authenticator Apps and Passkeys

The method matters

Multi-factor authentication adds a check beyond a password, but the checks are not interchangeable. Choose methods based on the service, device support, risks and how users will recover access. A stronger sign-in process still needs careful administration.

Compare the experience

• SMS or voice: familiar to many users, but dependent on the phone number and telephone service.
• Authenticator codes: generated in an app; users can still be tricked into entering a code on a fake page.
• Push approvals: convenient, but staff must recognise unexpected prompts and report them.
• Passkeys or FIDO2 security keys: can provide phishing-resistant authentication when supported and correctly configured.

Do not treat every app approval as phishing-resistant

A code copied from an authenticator app is different from a passkey. Ask your provider to explain which method the service will accept and what attack it is intended to reduce. Check the actual tenant configuration rather than relying on a product label.

No authentication method removes every risk. A compromised device, stolen session or inappropriate access can still matter after sign-in.

Plan the change

• Pilot with users who have different devices and working patterns.
• Check remote staff, shared devices and accessibility needs.
• Set up and test the approved account-recovery process.
• Record who can reset methods and how they verify identity.
• Prepare instructions for a lost phone or security key.

Keep the recovery path secure

Recovery should not become a shortcut around the stronger method. Avoid approving a reset merely because a caller knows a staff member's name. Store emergency access arrangements securely and test them with the responsible administrator.

For the related access-policy discussion, read our Conditional Access guide. NOX can help plan a rollout that fits your environment.

Official reference: Microsoft Conditional Access planning.