Your phone suddenly loses service: check for a SIM-swap attack

A sudden loss of cellular calls and texts can be an ordinary outage, but it can also mean a criminal moved your number to another SIM or device. That person may receive SMS verification codes and reset accounts tied to your number. Acting through the carrier's official channel is more important than repeatedly restarting the phone.

Before you start​

Find the carrier's official support details from your bill, account app or website opened independently. Have another phone or internet connection available.

Do it step by step​

1. Check whether other people on the same carrier and nearby location have service. Note the time service stopped and any SIM-change or port notification.
2. Contact the carrier immediately, report suspected unauthorized SIM or number transfer and ask it to restore control and secure the account.
3. Change the carrier account password and set a carrier PIN or available transfer lock. Record the case number and any unauthorized change time.
4. From a trusted device, secure email, bank and other high-value accounts. Replace SMS as a second factor with a security key or authenticator app where practical.
5. Inspect financial and account activity for unauthorized changes; report them promptly to the institution. Save evidence and use official identity-theft help if personal data was abused.

Check the result​

Calls and texts should reach your device again, the carrier should confirm the correct SIM, and affected accounts should show no unexplained sessions or transactions.

If something goes wrong​

A local outage or damaged SIM can look similar. The carrier can determine whether an account change occurred; do not send identity documents to someone who merely calls to 'help.'

Know the limit​

A carrier PIN is useful but not a guarantee. SMS-based account recovery remains vulnerable while a number is controlled by someone else, so review the recovery phone setting too. FTC SIM-swap response