How to hide your number when calling from a mobile or landline

You're about to call a second-hand listing, a business, or someone you don't know at all, and you'd rather your number didn't end up on their screen or in their call log. It's a perfectly legitimate need, and the phone network supports it out of the box: you can hide your number for one specific call with a short code, or permanently through your phone's settings. Here's how to do it on mobile and landline — plus the part almost nobody explains: what hiding your number actually achieves, and what it doesn't.

How do I hide my number for just one call?

The fastest way requires no settings at all: dial a short prefix before the number. Which prefix depends on where you are:

• In the UK, dial 141 before the number (e.g. 141 followed by the full number).
• In the US and Canada, dial *67 before the number.
• In most of Europe and on GSM networks generally, dial #31# before the number — it's the GSM standard code, and it works on both Android and iPhone.

Whoever receives the call will see "Private number", "Blocked" or "No caller ID" instead of your phone number.

The prefix applies to that call only: the next call you dial normally will show your number again. That makes it ideal for the most common use case — calling a stranger without handing over your number.

A practical trick: if you save a contact with the prefix included (for example, "Sofa listing" saved as #31# or *67 plus the number), every call to that contact goes out hidden without you having to remember the code.

How do I hide my number permanently?

If you want all your calls to go out unidentified, the setting lives in your phone's call configuration — and it works everywhere, regardless of country codes:

With permanent withholding on, the logic flips: if at some point you want to show your number on one specific call, dial the reveal code before the number — *31# on GSM networks (the mirror code of #31#), 1470 in the UK, *82 in the US and Canada.

Which should you choose? For most people, per-call hiding is more practical: you hide when you need to, and the rest of your calls stay identifiable — which avoids the problem you're about to read in the next section.

Will people even pick up if I call with a hidden number?

Here's the honest part you should know before switching anything on: more and more people silence or outright block hidden-number calls. Both iPhone and Android include options to send any unidentified call straight to voicemail, and many people have them enabled precisely because of spam and harassment. We explain it from the receiving end in calls from a hidden number: who's calling me?.

In practice, this means calling with a hidden number lowers your chances of getting an answer — especially when calling private individuals. If you call a listing and nobody picks up, your call may not even have rung. And the other person can't call you back even if they want to: they have no number to dial. For anything where you're expecting a reply, weigh up whether it's worth it.

Is it legal to call with a hidden number?

Withholding your number is a legal, legitimate feature of the phone network, designed precisely to protect your privacy. Using it as a private individual — to call a listing, a shop or any one-off matter — is completely fine.

That said, there are two important limits:

• Companies making sales calls generally can't hide who they are. Telemarketing rules in many countries require commercial callers to present a valid, identifiable number you can call back. If you receive advertising from a hidden number, that company is already breaking the rules — one more reason to distrust the call. You can see which commercial numbers rack up the most complaints in our spam number directory.
• Whatever is illegal with a visible number stays illegal with a hidden one. Withholding your number doesn't make harassment, threats or repeated prank calls acceptable.

Does hiding my number make me anonymous?

No — and this is the most dangerous misunderstanding around these codes. The withholding works only towards the person you're calling: their phone doesn't receive your number. But the network knows perfectly well who is calling whom: your carrier logs the origin and destination of every call, hidden or not.

That means if someone uses a hidden number to harass, threaten or repeatedly disturb another person, the victim can report it, and carriers can identify the origin of those calls and hand it to the authorities. The process exists and gets used; we cover it in detail in anonymous harassment calls: how to report them. Hiding your number protects your privacy from a stranger; it does not protect you from the consequences of misusing it.

By the way: the hide-your-number code is just one of several standard codes your phone understands. If you're curious, the rest are explained in secret phone codes that actually work.

Frequently asked questions

Does the code work with every carrier? With the major carriers, yes — these are network standards (GSM's #31#, the UK's 141, North America's *67). On some lines (especially landlines or VoIP) a given code may not be available; if it doesn't work, ask your carrier how to manage withholding on your line.

Does hiding my number cost anything? No. Both the per-call codes and the permanent setting are free network features.

Can I hide my number when sending texts or WhatsApp messages? No. Caller-ID withholding applies to voice calls. A text always carries your number, and WhatsApp is tied to your number by design.

I have permanent withholding on — how do I show my number just once? Dial the reveal code before the number: *31# on GSM networks, 1470 in the UK, *82 in the US and Canada. That one call goes out identified; the rest stay hidden.

Can the person I call find out my number with some app? No. If withholding is active, their phone never receives your number, and no app can display what never arrived. Only the carrier — faced with a police report — can identify the origin.

In short

Hiding your number is easy and legitimate: a short prefix before the number for a single call (141 in the UK, *67 in North America, #31# on GSM networks), the caller ID setting to make it permanent, and the mirror code to show yourself selectively if you're permanently hidden. Use it to protect your privacy from strangers, knowing its limits: plenty of people no longer answer hidden calls, companies can't hide behind them, and if someone misuses the feature, the network knows exactly who's calling.

And if your problem is the opposite — unknown numbers calling you — checking takes seconds: look the number up in NoCall's spam number directory and see whether other users have already flagged it. If a number is bothering you, report it: every warning helps the next person.