How to hide your phone number when calling

There are three ways to stop your number appearing on someone's screen, and they are not equivalent. A per-call prefix withholds your caller ID for one call — free, instant, and forgotten the moment you hang up. An always-on block does the same for every outgoing call, set once on the handset or by your carrier. A second number does something different: instead of showing nothing, it shows a different real line, so your own number is never transmitted at all.

The first two hide the number. The third replaces it — and that distinction decides whether the call actually gets answered. The table below sets the three side by side.

Dial a short prefix immediately before the number, with no space, then place the call as normal. The code is set by the network your line belongs to, not by the country you are dialling:

• United States and Canada: *67 — for example, *67 212 555 0134.
• United Kingdom: 141.
• Most GSM networks (Germany, Spain, Italy, the Netherlands, much of Asia): #31#.
• France: #31# from a mobile, 3651 from a landline.
• Australia: 1831. Japan: 184.

Two rules apply everywhere. Dial the number in full after the prefix — tapping a saved contact will not carry the code. And the prefix is ignored for emergency services and, in most countries, for toll-free numbers: those lines are entitled to your number whatever you dial.

If you never want your number sent, set it once instead of remembering a prefix:

• iPhone: Settings → Phone → Show My Caller ID, then switch it off. The row only appears when your carrier supports the setting — on several US carriers it is missing entirely and the change has to be made in the carrier's own account portal.
• Android: Phone app → Settings → Calling accounts → your SIM → Additional settings → Caller ID → Hide number. The exact path moves between manufacturers.
• Carrier level (CLIR): most operators will set permanent line identification restriction on request, which survives handset changes and SIM swaps.

With an always-on block you can still reveal your number for one call by dialling the inverse prefix: *82 in the US and Canada, 1470 in the UK, *31# on GSM networks.

Hiding your caller ID works perfectly — and that is the problem. A call with no number attached is exactly what a spam call looks like, so it meets the same machinery:

• iOS Silence Unknown Callers sends every withheld call straight to voicemail without ringing.
• Android call screening and carrier spam filters do the same, often without leaving a missed-call entry.
• Anonymous call rejection is offered by most operators and by nearly every business phone system: the call is refused at the network before it rings.
• People simply don't answer. "No Caller ID" reads as a debt collector or a scam to most recipients.

And there is no way back. The person you called cannot return the call, cannot text you, and has nothing to save as a contact. If the point of the call was to be reachable — a buyer, a client, a landlord, a candidate — hiding your number defeats it.

The alternative is to keep caller ID switched on and make it a different number. A second, dedicated line gives the recipient something real to see: a local number with a dial code they recognise, which rings through every filter a withheld call trips.

A PrivacyNumber line is a real local mobile or landline number in one of 47 countries, dialled and answered from a browser panel — no SIM, no app, no identity check, crypto-only billing. Outbound calls leave from that line, so your own number is never transmitted, never logged by the recipient's carrier and never stored in their phone. The caller ID on the line is yours to set: keep it fixed, hide it, rotate it, or present another number you own — from the panel or through the REST API.

Because the line is long-term rather than a burner, it also does what a hidden number cannot: it takes the call back, receives the SMS, and holds voicemail with transcription. See long-term numbers vs burners for where that difference bites, or pricing for what a second line costs.

Withholding your caller ID is legal for individuals almost everywhere. In the United States the Truth in Caller ID Act bans transmitting misleading or inaccurate caller ID with intent to defraud, cause harm or wrongfully obtain something of value — it does not ban withholding it. The UK, the EU and Australia take the same line. Businesses placing marketing calls are the exception: they are generally required to present a valid, dialable number.

What no prefix hides: your carrier knows exactly which line placed the call and keeps the record; emergency services receive your number regardless; toll-free numbers can capture it from the billing stream (ANI) even when caller ID is withheld; and a lawful request can surface all of it. Hiding your caller ID is a courtesy layer against the person you are calling, not a shield against the network. If you want your number to stay out of a company's records altogether, don't withhold it — don't give it to them.