SIM swapping

What it is

With your number, attackers can intercept SMS one-time codes, reset passwords, and break into email, banking, and crypto accounts. It often starts with social engineering the carrier or using leaked personal data to pass verification.

Sudden loss of signal is not always a network outage — it can be the first sign your number was ported away.

How it works

1. Recon — Attackers gather your number, account details, and PII.
2. Carrier fraud — They impersonate you to request a SIM change or port-out.
3. Cutover — Your phone loses service; theirs activates on your number.
4. Account resets — SMS codes let them into email, social, and financial apps.
5. Cash out — Transfers, crypto drains, or further takeovers.
6. This is a common prelude to high-value account takeover.

Red flags

• Sudden No Service while others nearby have coverage
• Texts or calls stop arriving; friends say your number works for them
• Carrier emails about a SIM change or port you did not request
• MFA codes you did not trigger
• Banking or crypto apps showing new device logins right after signal loss
• Difficulty logging into accounts that rely on SMS verification

What to do if you’re targeted

• **Contact your carrier immediately** from another phone; request a SIM freeze / port freeze and reclaim your number.
• **Secure email first**, then banks and crypto; switch MFA from SMS to an authenticator app or security key where possible.
• **Tell your bank** about possible SIM swap fraud; watch for transfers.
• **Change passwords** on high-value accounts and revoke sessions.
• **Ask the carrier** about extra account PINs or port-out protections.
• **Report** to ReportFraud.ftc.gov (U.S.) and consider a free identity scan if PII was used to social-engineer the carrier.

Related terms

• Account takeover
• Social engineering
• Identity theft