What is SIM swap fraud?

SIM swap fraud happens when a criminal gets your mobile number moved to a SIM or eSIM they control. Your phone may lose service while the criminal receives calls and text messages intended for you, including some security codes. They do not need to steal your physical phone. 1

By Secordit. Last checked: 7 November 2026.

Go to the steps · All glossary terms

How it works

  1. The criminal obtains information that helps them impersonate you. 1
  2. They persuade your mobile provider to move the number. 1
  3. Calls and texts reach their SIM, allowing further attempts on your accounts. 1

Real UK example

Which? reported Joanne’s case in April 2026. Her number was moved after a request she had not made. She alerted Vodafone but waited for it to be recovered.

During that period, criminals intercepted security codes from her bank and email provider. Which? checked the recovery delay with Vodafone. 1

Warning signs

  • A SIM change or number-transfer message you did not request. 1
  • Unexpected loss of mobile service. 1
  • Changes to your mobile account that you did not make. 1
  • A caller asks you to read out a mobile-account code. 1

What to do now

  1. Contact your network through webchat or another phone if a swap is suspected. 1
  2. Tell your banks that your mobile number may be compromised. 123
  3. Use a trusted device to secure your email and other important accounts. 1

UK reporting and support

  • If money has gone or banking details were shared, call your bank using the number on your card. Or use 159 if your bank participates. 234
  • Report fraud or hacking in England, Wales or Northern Ireland to Report Fraud. In Scotland, call Police Scotland on 101. 35
  • If someone is in danger, call 999. 5

How to protect yourself

  • Ask your network about extra checks for SIM changes. 1
  • Use a unique password for your mobile account and email. 1678
  • Where offered, consider passkeys rather than relying only on text-message codes. 1

Frequently asked questions

Does “No service” always mean a SIM swap?

No. It is not proof. But an unexpected SIM-change message alongside lost service is a reason to contact your provider. 1

Can criminals swap an eSIM?

Yes. Which? describes number transfers to physical SIMs and digital eSIMs. Provider checks matter in either case. 1

Who should I contact after a suspected SIM swap?

Contact your network and your banks. Then secure important accounts and report the fraud. 1

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General information, not legal, financial or personalised security advice. Secordit is not a police or bank reporting service.

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Sources

  1. Which?, Mobile networks must step up to prevent Sim-swap fraud - Which?. Accessed 7 November 2026 (Europe/London).
  2. UK Finance, Authorised Push Payment Fraud Reimbursement | UK Finance. Accessed 7 November 2026 (Europe/London).
  3. Report Fraud, Report Fraud alert: Police forces being impersonated in scam calls using ‘spoofed’ phone numbers - Report Fraud. Accessed 7 November 2026 (Europe/London).
  4. Stop Scams UK, 159 Phone number - Stop Scams UK. Accessed 7 November 2026 (Europe/London).
  5. Police Scotland, How to report a crime - Police Scotland. Accessed 7 November 2026 (Europe/London).
  6. NCSC, Recovering a hacked account | National Cyber Security Centre. Accessed 7 November 2026 (Europe/London).
  7. NCSC, Top tips for staying secure online | Turn on 2-step verification (2SV) | National Cyber Security Centre. Accessed 7 November 2026 (Europe/London).
  8. ICO, 23andMe fined £2.31 million for failing to protect UK users’ genetic data | ICO. Accessed 7 November 2026 (Europe/London).