What it means
A SIM swap or unauthorized port moves a phone number to a device controlled by someone else. A tower outage or broken SIM can also stop calls, but does not by itself deliver your SMS codes to an attacker. The carrier's account-change record is the decisive check.
A real-world example
One person's phone loses service while family members on the same network are fine, and the carrier confirms a new SIM was activated without permission.
What to do
Contact the carrier through official support, regain the number, secure the carrier account and inspect email and financial accounts that use text-based recovery.
The distinction that matters
A signal icon or Wi-Fi calling state may confuse the diagnosis. Do not wait for perfect certainty before reporting a suspected transfer. A carrier PIN and non-SMS second factor reduce risk but do not replace review of account-recovery settings.
FTC SIM-swap signs and response
