How to Block Your Phone Number When Making Calls

Blocking your phone number before making a call — so the recipient sees "Unknown," "Private Number," or "No Caller ID" instead of your digits — is a straightforward feature built into virtually every phone and carrier. But the exact method depends on your device, your carrier, and how consistently you want the block applied.

Here's how it works, what your options are, and where the differences actually matter.

What "Blocking" Your Number Actually Does

When you block your number, you're activating a feature called Caller ID suppression. Specifically, you're sending a signal through the phone network instructing the receiving end not to display your number.

This works through a system called CLIR — Calling Line Identification Restriction — a standard built into both GSM (used globally) and CDMA (used primarily in North America) networks. It's a network-level instruction, not something your phone app does independently, which is why it generally works regardless of what phone the other person is using.

One important caveat: some recipients can still receive your number on their end, even when suppressed. Emergency services (911 in the US) can always see your number. Some business phone systems and VoIP services are configured to unmask withheld numbers. And certain carriers offer "anonymous call rejection" services that will block your call entirely rather than put it through.

Method 1: Per-Call Blocking With a Dial Code 📞

The quickest way to block your number for a single call is to dial a prefix before the number:

So in the US, if you want to call 555-867-5309 without showing your number, you'd dial: *67-555-867-5309

This method works on both smartphones and landlines, and it applies only to that one call. Your number displays normally on every other call you make. No settings are changed. No account adjustments needed.

Method 2: Hiding Your Number by Default in Phone Settings

If you want every outgoing call to go out with your number suppressed — without dialing a code each time — both major mobile platforms let you change this in settings.

On iPhone (iOS): Go to Settings → Phone → Show My Caller ID and toggle it off.

On Android: The path varies by manufacturer, but generally: open the Phone app → tap the three-dot menu or Settings → Calls → Additional Settings (or Supplementary Services) → Caller ID → select Hide Number.

Some Android devices label this differently depending on the manufacturer skin (Samsung One UI, Pixel's stock Android, and others all have slight variations in menu naming).

⚠️ Important: Not all carriers allow this setting to function. Some carriers — particularly prepaid networks and MVNOs — override this setting at the network level, and the toggle may appear to do nothing. If you flip it off and your number still shows, the restriction is coming from your carrier, not your phone.

Method 3: Requesting Permanent Suppression Through Your Carrier

Most major carriers in the US, UK, and Australia offer permanent Caller ID blocking at the account level — sometimes free, sometimes tied to a specific plan. This is configured in your account settings or by calling customer support.

If permanent blocking is active on your line, you can then use a per-call unblock code to reveal your number for specific calls:

This is essentially the inverse scenario — your number is hidden by default, and you opt in to showing it when needed.

How This Works Differently on VoIP and Apps

If you're making calls through apps like WhatsApp, FaceTime, Google Voice, Skype, or Zoom Phone, the Caller ID rules change.

• WhatsApp and FaceTime show the name/number associated with your account. Dialing codes like *67 have no effect because these calls travel over the internet, not the traditional phone network.
• Google Voice gives you a separate number — the recipient sees your Google Voice number, not your actual SIM number, inherently giving you separation.
• VoIP business services vary widely. Some pass through Caller ID from your underlying carrier; others let you configure what's displayed.

If Caller ID suppression matters for app-based calls, you'd need to look at each app's own privacy settings rather than relying on carrier-level codes.

The Variables That Determine What Works for You

How well number blocking works — and which method makes sense — shifts depending on a few key factors:

• Your carrier: Some allow default suppression; others override it entirely
• Your phone's OS and version: Menu paths and toggle availability vary
• How often you need it: Per-call codes suit occasional use; settings-level changes suit frequent or default suppression
• What type of calls you're making: Traditional cellular calls vs. internet-based calls follow different rules
• Who you're calling: Some recipients have anonymous call rejection active, which means suppressing your number may prevent the call from going through at all

The right approach for someone who occasionally wants privacy on one-off calls is genuinely different from someone who wants their number permanently withheld — and both are different from someone making calls through business VoIP. Your specific carrier's policies, your device, and how consistently you need suppression all shape which method will actually work as expected.