Glossary
What is SIM swap?
A SIM swap moves a mobile number onto a new SIM card. Done fraudulently, it lets a criminal receive the victim's texts, including one-time codes sent to that number.
Ofcom's 2022 policy statement on scam calls and texts describes the fraud: the scammer "tricks a mobile provider into providing a new SIM card for an account that does not belong to the scammer", and the victim's own SIM stops working. A related fraud, porting, moves the number to another network instead.
Cifas, which runs the National Fraud Database, counted 289 unauthorised SIM swaps in 2023 and nearly 3,000 in 2024, then reported a 402% rise in the first half of 2026 on the same months of 2025.
A customer who rings to say their phone lost all service without warning may be the victim of one, so it's worth holding anything that depends on a texted code until the number is back with them. Some mobile networks offer checks based on the CAMARA SIM Swap API, which tells a business whether a number's SIM changed recently.
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