Why is an SMS code for two-factor authentication less secure than an authenticator app?

SMS MESSAGES ARE VULNERABLE TO INTERCEPTION VIA SIM SWAPPING AND SS7 PROTOCOL ATTACKS.

Codes in text messages are transmitted unencrypted over the cellular network. Attackers can reissue a SIM card using a fake power of attorney or intercept incoming carrier traffic to gain account access.

Cellular Network Vulnerabilities

The SS7 signaling protocol, used for routing cellular calls and messages, was designed without modern security standards in mind. Attackers can remotely redirect SMS delivery to a controlled number, whereas software-based TOTP generators create temporary one-time keys directly within the device's isolated memory without involving the network.

How to Protect Critical Accounts

Disable phone number login verification across all supported services
Link an autonomous code generator app (such as Aegis, 2FAS, or Google Authenticator)
Save one-time backup recovery codes in an encrypted password manager
Set a ban on SIM card reissuing via power of attorney at your mobile carrier's store