SIM Swapping in the UK: What It Is and How to Protect Yourself

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What is SIM swapping?

Mobile networks allow customers to transfer their number to a new SIM card, a legitimate feature for when you get a new phone. Attackers exploit this by impersonating you to your network, claiming to have lost their SIM and requesting a transfer. Once successful, your number routes to their SIM and you lose service.

With your phone number, attackers can intercept SMS two-factor authentication codes
They can trigger "forgot password" flows that send verification codes to "your" number
A successful SIM swap can give access to your bank accounts, email, and social media within minutes
UK networks must verify identity before carrying out a SIM swap, but social engineering can defeat these checks

4 steps

Warning signs that a SIM swap is happening

The most immediate sign is that your phone loses service: calls and texts stop working:

Your phone suddenly shows "No service" or "Emergency calls only" outside of poor coverage areas
You receive unexpected texts asking you to confirm a SIM change you did not request
You receive unexpected 2FA codes for accounts you are not trying to access
Your mobile network app sends an alert about account changes
Act immediately: call your network from a different phone and ask them to freeze your account

5 steps

How to protect yourself

These steps significantly reduce your SIM swap risk:

Use an authenticator app for 2FA instead of SMS: authenticator codes cannot be intercepted via SIM swap
Set a network PIN or "port freeze" with your mobile provider (most UK networks offer this); it adds an extra check before number transfers
Limit the personal information publicly available about you (full name, date of birth, address): this is the data attackers use to social-engineer your network
Use a unique, strong email address and password for your mobile network account
Enable 2FA on your mobile network account if they offer it
Be cautious of unexpected texts asking you to call a number or confirm details

6 steps

What to do if you are a victim of SIM swapping

Time is critical: act on all of these as quickly as possible:

Call your mobile network from a different phone immediately and report the SIM swap
Contact your bank if you have linked any accounts to that phone number
Change your email password and enable 2FA using an authenticator app
Report to Report Fraud: reportfraud.police.uk or 0300 123 2040
Review your accounts for any changes or transactions you did not authorise

5 steps

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SIM swapping: what it is and how to protect yourself

What is SIM swapping?

Warning signs that a SIM swap is happening

How to protect yourself

What to do if you are a victim of SIM swapping