Using Your Mobile Number Safely Online

We hand out our mobile numbers constantly: at checkouts, on delivery forms, when signing up for apps and competitions. Each time, there's a chance it ends up on a marketing list, gets exposed in a data breach, or is sold on. You can't keep your number completely private, but you can be a lot more careful with it.

Think before you share

Ask yourself whether the organisation actually needs your number. A delivery driver might. A shop's loyalty scheme, a competition entry or a free Wi-Fi login usually doesn't. If a number field is optional, leave it blank.

Read the tick boxes

Forms often include pre-ticked or confusingly worded boxes allowing "carefully selected partners" to contact you. Untick them. Under UK rules, companies generally need your consent before sending you marketing texts.

Lock down your social media

• Remove your number from your public profile.
• Check the settings that let people find you by phone number, and turn them off if you don't need them.
• Be careful about posting photos of documents, parcels or screens that show your number.

Use a second number for some things

For online selling, dating apps or classified adverts, a second number keeps your main one private. Many phones support a second line through an eSIM, and some apps provide a separate number that rings on your phone.

Protect the accounts linked to your number

• Set a PIN or password on your mobile network account to make SIM swap fraud harder.
• Where possible, use an authenticator app or passkeys rather than text codes for important accounts.
• Never share a code that arrives by text unless you asked for it yourself, a moment ago.

If your number is already getting spam

• Register with the Telephone Preference Service to cut legitimate sales calls.
• Reply STOP only to companies you recognise. Replying to unknown senders confirms your number is active.
• Switch on spam filtering or silence unknown callers in your phone settings.
• Look up unknown numbers on Who Called Me Check before answering or calling back, and report the ones that turn out to be spam.

Changing your number

If the calls get really bad, changing your number is a last resort. Before you do, list everything linked to the old number (banks, email recovery, apps) and update them first, or you could lock yourself out.