We all know the importance of 2FA (Two-Factor Authentication). This process requires the use of SMS or App-Based Authenticators. But let’s start with 2FA first up. If it is a new concept for you, it’s basically a security process that requires two different forms of identification to access an account. Typically, those forms are something you know (like a password) and something you have (like a code from an authenticator app or SMS). This extra layer makes it much harder for attackers to gain unauthorised access.
The question then becomes, “which do I use? An authenticator app or SMS on my mobile device?” Here’s why app-based authenticators are more often advised by online security folks, than the good old text.
SMS Is Vulnerable to SIM Swaps
Attackers can hijack your phone number by convincing your carrier to transfer it to a new SIM card. Once they control your number, they can intercept 2FA codes sent via SMS and access your accounts.
SMS Can Be Intercepted
SMS messages travel through cellular networks, which can be tapped or spoofed. In some cases, malware or rogue apps can read SMS messages on compromised devices.
App-Based Codes Stay on Your Device
Authenticator apps generate codes locally, without relying on network transmission. This means no one can intercept them remotely. They are tied to your device, not your phone number.
Time-Based One-Time Passwords (TOTP) Are More Resilient
Apps like Authy and Google Authenticator use TOTP algorithms that refresh every 30 seconds. Even if someone sees a code, it becomes useless almost immediately.
Better for Travel and Remote Work
SMS may not work reliably when traveling internationally or using virtual numbers. Authenticator apps work offline and across devices, making them ideal for VAs and distributed teams.
Comparison: SMS vs App-Based Authenticators
Here’s a clearer look at the pros and cons of SMS in relation to app-base authentication.
| Feature / Risk Area | SMS Based 2FA | App-Based Authenticator |
| SIM Swap Vulnerability | High risk. Attackers can hijack your number via carrier manipulation | No risk. Codes are tied to your device, not your phone number |
| Message Interception | Can be intercepted via cellular networks or malware | Codes are generated locally and never transmitted |
| Code Storage and Security | Stored in messages making it vulnerable to rogue apps | Stored securely in the app and is often encrypted |
| Code Expiry and Rotation | In many cases it is static until received | TOTP refreshes every 30 seconds so the codes expire quickly |
| Travel and Remote Work Reliability | May fail with international SIMs or virtual numbers | Works offline and across devices making it ideal for remote teams |
| Multi-Device Access | Not supported | Supported (eg. Authy sync with encryption) |
| Setup for Teams / VAs | Difficult to delegate securely | Supports role-based access and shared login workflows |
FAQs: App-Based Authenticators and SMS
Can I use both SMS and app-based authentication for the same account?
Yes, but it’s not recommended. If both are enabled, attackers may still exploit the weaker method (SMS). Choose the most secure option and disable fallback to SMS where possible.
What if I lose access to my authenticator app or device?
Use backup codes or recovery options. Most apps (like Authy or Google Authenticator) offer secure backup or device sync. Always store recovery codes offline in a password manager.
Is Authy safer than Google Authenticator?
Authy offers encrypted multi-device sync and backups, which can be helpful for VAs or distributed teams. Google Authenticator is simpler but lacks backup and sync features.
Can I share 2FA access with my VA securely?
Yes, but be careful. Use tools like 1Password or Bitwarden to share logins without exposing raw codes. Alternatively, create role-based accounts with their own 2FA setup.
Do authenticator apps work offline?
Yes. They generate time-based codes locally, so no internet or cellular connection is needed. This makes them ideal for travel or remote work.
How do I migrate my 2FA codes to a new phone?
Use the app’s export or sync feature. For example, Authy allows encrypted sync across devices. ALWAYS test recovery before decommissioning your old device.
Find out more about how to safely share passwords with your Virtual Assistant.
