Your phone suddenly shows “No Service” and never comes back, even though the network is fine for everyone around you. Minutes later, you cannot log into your email or bank. These are the warning signs of a SIM swap — when a scammer hijacks your phone number to intercept your codes. Spotting it fast is everything. Our GetMyPassword team explains the signs and what to do.
What a SIM swap does
In a SIM swap, a scammer convinces your carrier to move your phone number to a SIM card they control, often using personal details gathered from leaks or phishing. Once they have your number, every text message and call meant for you goes to them — including the one-time codes that protect your accounts. With your number and those codes, they can reset passwords and break into email, banking and more. Your phone, meanwhile, goes dark.
Warning signs to watch for
- Sudden, lasting loss of service — “No Service” or “SOS only” when others have signal.
- You stop receiving calls and texts, or get a notice your number was activated on a new device.
- Unexpected “your password was changed” emails for your accounts.
- Being locked out of email, banking or social accounts you did not touch.
- Alerts from your carrier about a SIM or plan change you did not request.
What to do immediately
Move fast, because the attacker is racing through your accounts. Contact your mobile carrier right away — from another phone — to report the swap and reclaim your number. Then secure your most important accounts, starting with email, by changing passwords from a device you trust. Check for and undo any unauthorized changes, and alert your bank to watch for fraud. The sooner you cut off their access to your number, the less they can do.
A phone that goes dark while everyone else has signal is not a glitch to ignore — it can be the first minute of an account takeover. Treat sudden, lasting loss of service as a reason to act, not wait.
How to reduce the risk
Add a carrier PIN or port-out lock to your mobile account so your number cannot be moved without it. Where possible, protect accounts with an authenticator app or a security key rather than text-message codes, since those do not travel with your number. And keep every account behind a unique password from our password generator, so even if your number is stolen, a single hijacked code cannot unlock everything.
Frequently asked questions
What are the warning signs of a SIM swap?
A sudden, lasting loss of mobile service when others have signal, no longer receiving calls or texts, unexpected “password changed” emails, being locked out of accounts, and carrier alerts about a SIM or plan change you did not request.
What should I do if my number was SIM swapped?
Contact your carrier immediately from another phone to report it and reclaim your number, then change passwords on your key accounts — starting with email — from a trusted device, undo unauthorized changes, and alert your bank to watch for fraud.
How do I prevent a SIM swap?
Add a carrier PIN or port-out lock so your number cannot be moved without it, protect accounts with an authenticator app or security key instead of text codes where possible, and use a unique password for every account.