Securing accounts when you lose or change an old phone number

Katerina Galkina · EN · 07/10/2026

List connected services

Check email, banks, government accounts, messaging, shops and social media. A number may be a login, notification contact or recovery method; these are separate fields. Changing one does not necessarily update the others.

While you still control the number, update essential accounts before ending service. To retain it, use Ofcom's official switching guidance ↗. Do not assume an unused SIM remains yours indefinitely; check your operator's activity rules.

Strengthen account recovery

NCSC recommends two-step verification ↗. Choose supported methods you can reliably manage, such as an authenticator, security key or other available option. Store backup codes securely apart from the everyday device.

Update recovery email and review active sessions. Avoid removing protection merely to simplify a number change. A reliable backup method for primary email matters because it can recover many other accounts.

If the old number is already unavailable

Contact the operator and services through official channels. Explain when control was lost and complete their identity checks. Asking a number's new holder to forward banking codes creates unsafe dependence and disclosure.

Do not use someone else's codes accidentally sent to your new number. Receiving a text does not make the account yours. Report an incorrect contact through the service's process rather than attempting to enter another person's account.

Suspected takeover

Unexpected loss of service alongside account-change alerts warrants prompt operator and bank contact through known channels. Restrict affected access as instructed. Check email and important accounts from a trusted device.

Record events, times, alerts and case references. Do not disclose codes to an unsolicited caller claiming to be security staff. Planned number changes take effort but are usually easier than recovering many accounts after losing control.