Sim swap fraud is different to a phishing scam where fraudsters trick you into handing over your bank details and passwords via a link to a dodgy website. Instead, fraudsters target your mobile network provider in order to trick them into swapping your phone number on to a card controlled by the hackers.

Fraudsters use this kind of scam when they already have access to your online banking, but can’t transfer any money out of the account. This is normally a unique code that is sent to your nominated phone number – the number you chose to be associated with your bank – so that you can enter it in to your online banking to complete the transaction.

To get access to your phone, fraudsters convince your mobile phone network provider to swap your number on to a new sim card that the scammers control. They know what network you’re with because they can see the bills you pay from your account. Different networks ask for different information to make the swap, but some only require your phone number and the serial number of the new sim. It can take up to 24 hours to move your number from one sim to another but it can be done much quicker. This is because banks often use two-step authentication when you’re setting up a new payee. The fraudsters then intercept your messages and use the code to illegally transfer your money out of your account. But normally, banks can detect the fraudulent activity and stop it from going any further as long as you have the account.

What should I do if scammers swap my sim card?

If you notice that your phone has unexpectedly lost all signal then you should contact your network provider straight away. They may be able to block the swap before it is moved on to the scammer’s sim card. Don’t turn your phone off if you’re getting a lot of nuisance calls because this can be a tactic used by scammers to make the process easier. Again, you should call your network provider as soon as you can. Check your online banking too and look out for any payments that have been made without your authorisation. Contact your bank too so that they can temporarily lock the account while you change your passwords.