SMS codes vs. authenticator apps
Any second factor beats a password alone, but authenticator apps and security keys resist attacks that defeat text-message codes. What to require, and where.
Multi-factor authentication is one of the most effective security controls a small business can adopt. Not all second factors are equally strong, though. Codes sent by text message are convenient but vulnerable to SIM swapping and interception. Authenticator apps and hardware keys are harder to steal.
Choosing the right factor for each system balances security with what people will actually use.
SMS codes
A one-time code sent by text message to a registered phone number. It is easy to set up and familiar, but attackers can sometimes redirect a phone number through SIM swapping or trick users into sharing the code.
Authenticator apps
An app on the user's phone generates time-based codes or approves sign-ins with a push prompt tied to the device. Codes never travel over the phone network, which makes them harder to intercept.
Side by side
| Factor | SMS codes | Authenticator apps |
|---|---|---|
| Setup | Enter a phone number | Scan a QR code |
| Resistance to SIM swap | Weak | Strong |
| Resistance to phishing | Weak | Moderate; strongest with number matching |
| Works offline | No | Yes, for code-based apps |
| Recovery planning | Phone number change process | Backup codes or a second device |
Choose sms codes when
- The system offers nothing stronger.
- It is a temporary step while rolling out app-based MFA.
- The account is low-risk and the user has no smartphone.
Choose authenticator apps when
- The account holds email, client data, financial access, or admin rights.
- You can give staff a short setup walkthrough.
- You want to meet insurer and regulatory expectations.
The bottom line
Require authenticator apps, or hardware security keys for administrators, on email, remote access, financial accounts, and any system with client data. Use SMS only where nothing better is available. Any MFA is far better than none. See multi-factor authentication.
Still deciding?
Bring the decision to a short call. We will tell you which option we would choose in your position, and why.