SIM swap fraud UK: how to protect your phone number
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Last checked: 25 October 2026
Short answer: To protect your phone number from SIM-swap fraud, ask your mobile provider what extra account security it offers, such as a PIN or password needed to approve account changes. Set a voicemail PIN too. Stop relying on text-message codes for your email and bank where a passkey or app is offered. If your phone suddenly loses service, contact your provider, then your bank.
If your mobile number is also your business line, it probably receives your bank codes and email codes as well. That's exactly what makes it worth stealing. As Which? puts it, "criminals know that your phone number is the key to unlocking your finances".
What is a SIM swap scam?
A criminal persuades your mobile provider to switch your number to a new SIM card, or a digital eSIM, that they control. Which? explains what happens next: "your phone loses network connectivity, and the fraudster receives all your calls and texts". That includes the one-time codes your bank and email send by text.
To get past the provider's checks, scammers gather personal details about you from social media, previous data breaches or phishing messages and calls.
Does an eSIM make you safer? Not on this point. Which? says your risk "depends on the security checks set up by your mobile network, regardless of whether you have a physical or virtual Sim".
Is SIM-swap fraud rising in the UK?
Cifas, the UK fraud prevention service, says unauthorised SIM swap cases recorded by its members on the National Fraud Database rose 38% in 2025 compared with 2024 (Fraudscape 2026). Its August 2026 update said cases in the first six months of 2026 were 402% higher than in the same period of 2025.
Earlier figures point the same way. Reports of SIM-swap fraud to Report Fraud (formerly Action Fraud) rose from 558 in 2022 to 1,070 in 2023. By the end of November 2024 they had reached 2,037. Which? obtained those figures and notes that the reports are self-reported, so they "may not have been verified". Action Fraud suggested at the time that the rise was likely due to an increase in public awareness of SIM swapping.
Getting a stolen number back isn't always quick, either. In one case Which? reported, a victim waited 10 days for her number to be recovered.
How do I stop a SIM swap on my number?
- Lock down your email first. In one case Which? reported, fraudsters "had got into his emails first". That let them reset the password on his mobile account and request the code to move his number to another network. Use a passkey on your email if your provider offers one, or a strong, unique password with 2-step verification (2SV).
- Add a PIN or password to your mobile account. Report Fraud says most phone providers have their own security options, such as a secret question or a personal PIN for your account, and that it's always worth checking what yours offers and signing up to use them. Ask your provider whether a PIN or password can be required before sensitive changes, such as a SIM swap.
- Set a voicemail PIN so only you can get to your messages. Call your voicemail service to do it.
- Move your email and bank off text-only codes where you can. Which? says SMS codes are "better than no 2FA at all", but it prefers passkeys "as they're tied to a physical device rather than your phone number".
- Clean up your public profiles. Avoid sharing your date of birth, pet names or phone number, and restrict who can see your social media profiles.
- Be wary of calls from your network's "fraud team". In two cases Which? reported, the scammer rang pretending to be just that. Never read out a code you've been texted to someone who called you.
Do UK mobile networks offer SIM-swap protection?
We haven't checked each network's settings, so ask yours what it offers. As one example, VodafoneThree told Which? its fraud teams offer customers "enhanced checks like multi-factor authentications for Sim swaps".
What should I do if my phone suddenly says "No service"?
Act quickly. Which? says to call your network straight away if you get an unexpected message about your SIM being moved, or a number transfer (PAC) request you didn't make.
If you've already lost service:
- Contact your network by webchat or by calling from another phone.
- Contact your banks so they can freeze your accounts.
- Change the passwords on your other important accounts, starting with email.
- Turn off text messages as a sign-in method where you can.
- Report it to Report Fraud at reportfraud.police.uk or on 0300 123 2040. In Scotland, call Police Scotland on 101.
If someone has got into your accounts, the NCSC's guide to recovering a hacked account takes you through the steps.
Scam texts can be forwarded to 7726. It's free.
Our printable After a Scam: What to Do First checklist has a "No service" step for when your phone suddenly loses signal.
Printable table: lock down your number
| Step | Where | Done? |
|---|---|---|
| Email: passkey, or strong password plus 2SV | Your email security settings | ☐ |
| Mobile account: PIN or password for changes | Your network's app, website or phone line | ☐ |
| Voicemail PIN | Call your voicemail | ☐ |
| Bank and email off text-only codes where possible | Each account's security settings | ☐ |
| Profiles: hide date of birth and phone number | Social media privacy settings | ☐ |
| "No service" plan: network's number and bank fraud line written down | Paper, kept somewhere safe | ☐ |
Running a small business? Our Small Business Cyber Starter Checklist covers the other basics, one topic at a time.
Our Account Lockdown Kit, a paid guide we sell, has a whole section on SIM-swap protection: what to ask your UK mobile provider, plus the email and 2-step steps that go with it. Get the Account Lockdown Kit
Ofcom has advice on protecting yourself from scam calls, texts and messages.
FAQ
What is SIM swap fraud?
A criminal gets your mobile network to move your number to their SIM or eSIM. Your calls and texts, including one-time codes, then go to them.
How do I protect my number in the UK?
Ask your network what extra account security it offers, such as a PIN or password for account changes, and set a voicemail PIN.
Are text-message codes safe?
They're better than no 2-step verification, but they can be intercepted after a SIM swap. Which? prefers passkeys.
Is an eSIM safer?
Which? says your risk depends on your network's security checks, whether the SIM is physical or virtual.
What do I do if I suddenly lose signal?
Contact your network from another device, then your banks. After that, change your key passwords.
