Protecting Your Phone Number From Takeover
Your phone number receives codes for your bank, mobile money and email. How criminals take numbers over, and practical protections: SIM PINs, network account security, and reducing exposure.
Your phone number has quietly become a key to your finances. It receives one-time codes for your bank and email, it may be your mobile money wallet, and it is how friends and family recognise you. If a criminal takes control of it, they can receive your codes and impersonate you. Here is how that happens and how to make it much harder.
How phone numbers are taken over
- SIM swap: a criminal convinces or bribes network staff to move your number to a SIM they control. See SIM swap fraud.
- Number porting: your number is transferred to another network. See number porting fraud.
- Network account takeover: someone gets into your online account with your mobile network and requests changes.
- Stolen phone: a thief with an unlocked phone can read your texts.
These attacks usually depend on personal details collected from social media, data breaches or earlier phishing.
Protections to set up
- Ask your network about extra protection for SIM changes and porting, such as an account PIN, password or in-person ID requirement, and turn it on.
- Secure your network account online with a unique password and two-step verification.
- Set a SIM PIN so a stolen SIM cannot be used in another phone. See setting a SIM PIN.
- Lock your phone with a strong PIN or biometrics. See screen lock.
- Hide text previews on your lock screen.
Reduce what relies on your number
- Switch important accounts from text codes to authenticator apps or passkeys. See SMS code weaknesses.
- Keep your number off public profiles where you can.
- Be careful about sharing ID details that could be used to impersonate you at a network shop.
If your phone suddenly loses service where it normally works, and it does not come back after a restart, call your network from another phone immediately and ask whether your SIM has been changed. Then call your bank.
Scams that target your number
- Fake network staff asking you to read out a code "to upgrade your SIM". See fake customer care calls.
- Messages saying your line will be blocked unless you "verify".
- Requests for photos of your ID and SIM pack.
Got a message about your SIM or line? Paste it into CyberWatch AI Scan for a free check, and call your network on its official number.
Your number is part of protecting your phone and number, one section of our complete guide.
Frequently asked questions
How do criminals take over a phone number?
Mainly through SIM swaps, where they persuade or bribe network staff to move your number to their SIM, and through porting your number to another network. Both usually rely on personal details they have collected about you.
What is the single best protection?
Ask your mobile network what extra protection it offers for SIM changes and porting, such as an account PIN or password, and set it up. Then reduce how much your accounts rely on text codes.
What are the warning signs of a SIM swap?
Your phone suddenly shows 'No service' or 'Emergency calls only' where it normally works, or you receive a message about a SIM change you did not request.
Sources
- How To Protect Your Phone From Hackers, US Federal Trade Commission
- Multifactor Authentication, US Cybersecurity and Infrastructure Security Agency
- Device security guidance, UK National Cyber Security Centre
