Question Identity
How do I know if I’ve been SIM swapped?
The clearest sign is that your phone suddenly loses service where coverage is normally fine, and calls and texts stop arriving. Other signs are a carrier notice about a SIM change or number transfer you didn’t request, and password-reset or new-login alerts from accounts you didn’t touch. Contact your carrier from another phone immediately.
How do I know if I’ve been SIM swapped? The clearest sign is that your phone suddenly loses service where coverage is normally fine, and calls and texts stop arriving. Other signs are a carrier notice about a SIM change or number transfer you didn’t request, and password-reset or new-login alerts from accounts you didn’t touch. Contact your carrier from another phone immediately. Source: https://glide-cleartext.pages.dev/q/how-do-i-know-if-i-have-been-sim-swapped/ (Cleartext, verified 2026-09-10)
Signs to look for #
- Sudden loss of service: no bars, no calls and no texts where your phone normally works. Your SIM stops working when the number is moved to someone else’s.
- A carrier notice you didn’t expect: a message or email about a SIM change, a new eSIM, or a request to transfer your number to another carrier.
- Security alerts from other accounts: password-reset emails, “new sign-in” notices or one-time passcodes you didn’t request.
Why carrier notices are the early warning #
The FCC’s 2023 rules require US wireless carriers to notify customers promptly when a SIM change or port-out is requested on their account.[1] That notice may be the first thing you see, so read carrier messages about account changes rather than dismissing them.
What to do first #
Call your carrier from another phone to stop the transfer and recover your number, then secure your email account, because that is where password resets for everything else land. In the US, the FTC’s IdentityTheft.gov builds a recovery plan and report.[2] Step by step: respond to a SIM swap.
Evidence #
Numbers match the citations in the text. Primary sources are the standard, regulation, regulator statement or dataset itself.
What this means for you #
Banks & credit unions
A customer reporting a sudden loss of phone service may be describing a SIM swap in progress. Route those calls to fraud, not general support, and review recent logins, payee additions and contact-detail changes.
Fintechs & payment firms
Give users a fast way to freeze their account from a second device or by email. The first minutes after a SIM swap are when funds move.
Developers & identity teams
Send security alerts to more than one channel. If the only alert for a password reset goes by SMS, a SIM-swapped user never sees it.
Follow-up questions #
- Can a SIM swap happen without me noticing?
- Rarely for long. When the number moves, your own SIM stops working on the network, so loss of service is usually visible within minutes.
- Where do I report it in the US?
- Your carrier first, to recover the number. Then your bank and the affected services, and the FTC at IdentityTheft.gov, which produces a recovery plan.
People also ask #
What is a SIM swap attack?
A SIM swap is when a criminal gets a mobile carrier to move a victim’s phone number to a SIM or eSIM they control, by impersonating the customer, bribing an insider or taking over the carrier account. The attacker then receives the victim’s calls and texts, including one-time passcodes and password-reset codes.
Full answerWhat does the FCC SIM swap rule require?
The FCC’s 2023 order, FCC 23-95, requires US wireless carriers to authenticate customers securely before moving their number to a new SIM or carrier, to notify customers of SIM-change and port-out requests, to offer account locks, and to train staff and keep records. It regulates carriers, not how banks or apps use SMS codes.
Full answerHow can banks defend against SIM swap fraud?
Stop treating an SMS code as proof of identity for high-risk actions such as password resets, new payees and contact-detail changes. Check whether the customer’s SIM changed recently before trusting the number, offer phishing-resistant sign-in such as passkeys, and send alerts about sensitive changes to a channel the attacker doesn’t control.
Full answerDecide and act #
Cite this answer #
Answers change. Include the verification date when you quote this page.
Plain text
Cleartext. “How do I know if I’ve been SIM swapped?” Last verified 2026-09-10 (rev. 1). https://glide-cleartext.pages.dev/q/how-do-i-know-if-i-have-been-sim-swapped/
Markdown link
[How do I know if I’ve been SIM swapped?](https://glide-cleartext.pages.dev/q/how-do-i-know-if-i-have-been-sim-swapped/) (Cleartext, verified 2026-09-10)
Changelog #
| Date | Revision | Change |
|---|---|---|
| Rev. 1 | First published. |