SIM swap
Definition
An attack where someone gets your carrier to move your number to their SIM so they receive your calls and codes.
SIM swap, explained
A SIM swap is fraud in which an attacker convinces your carrier, often with stolen personal details, to transfer your phone number to a SIM they control. Your phone loses service and the attacker starts receiving your calls and SMS codes, which they use to reset passwords on your accounts. Warning signs include sudden loss of signal and messages about a SIM change you did not request. To reduce the risk, set a PIN or passcode on your carrier account, turn on any number lock or port-out protection offered, and move important accounts from SMS 2FA to an authenticator app or passkey.
Related terms
Number porting
Moving your existing phone number from one carrier or provider to another so you keep the same number.
2FA (two-factor authentication)
Signing in with two different proofs, typically a password plus a code, app prompt, passkey or security key.
Authenticator app
An app that generates time-based login codes on your device, with nothing sent over the phone network.
Where you'll meet this term
Creating a Gmail or Google Account Without Your Phone Number
When Google asks for a phone number at sign-up and when it doesn't, how to verify a Gmail account with a virtual number, and how to secure it afterward.
Read the guide →Safety & privacyHow to Protect Your Phone Number From Spam, Data Brokers and SIM Swaps
Your phone number links to spam, data brokers, SIM-swap attacks and account takeover. Practical steps to protect it, and where a temporary number helps.
Read the guide →Safety & privacyWhat Is SMS Verification? How OTP Codes Work and Safer Alternatives
What SMS verification and one-time passcodes are, why sites use them, how codes are delivered, and how SMS 2FA compares to authenticator apps and passkeys.
Read the guide →Safety & privacyIs It Safe to Use a Virtual or Temporary Phone Number?
Are temporary and virtual numbers safe for verification? The real risks (recycling, recovery, public inboxes) and how to use one safely.
Read the guide →SMS codes vs Authenticator appSMS codes vs authenticator apps for 2FA
Authenticator apps resist SIM swaps and interception better than SMS codes. SMS 2FA is easier to recover. How each works and when to use which.
See the comparison →SMS verification vs Email verificationSMS verification vs email verification
Email verification is free and easy to recover; SMS is harder to fake in bulk but tied to a number you must keep. How they differ and when each fits.
See the comparison →