How to Block Your Number When Making a Call
Blocking your number when making a call — so the person you're calling sees "Unknown," "Private Number," or "No Caller ID" instead of your actual digits — is a built-in feature on virtually every modern phone. It's not complicated, but the method varies depending on your device, carrier, and how often you want the block applied.
What "Blocking Your Number" Actually Does
When you make a call, your phone transmits your number as part of the Caller ID signal (technically called CLID or CLI — Calling Line Identification). Blocking your number tells the network to suppress that signal before the call reaches the recipient.
This is different from blocking incoming calls. Outgoing number suppression hides your identity from the person you're calling. It doesn't prevent the call from going through, and it doesn't hide your number from emergency services (911 always receives your number regardless of suppression settings).
The Two Main Methods
Per-Call Blocking with a Prefix Code
The most widely supported method is dialing *67 before the number you're calling (in the US and Canada). The full dial string looks like:
*67-XXX-XXX-XXXX This suppresses your Caller ID for that single call only. Your number shows normally on every other call. It works on most landlines, Android devices, and iPhones without any settings changes.
Outside North America, the prefix differs:
| Region | Prefix Code |
|---|---|
| US & Canada | *67 |
| UK | 141 |
| Australia | 1831 |
| Most of Europe | #31# |
Always dial the prefix as part of the number string, not as a separate call. If you're calling internationally, place the prefix before the country code.
Permanent Number Blocking Through Settings
If you want every outgoing call to show as private by default, both Android and iPhone offer a setting to suppress Caller ID globally.
On iPhone: Settings → Phone → Show My Caller ID → toggle off
On Android: The path varies slightly by manufacturer, but generally: Phone app → Settings (three-dot menu or gear icon) → Calls → Additional Settings → Caller ID → Hide Number
Some Android skins (Samsung One UI, for example) label this differently — look for "Supplementary Services" or "More Settings" under Call Settings.
Important: These device-level settings send a request to your carrier to suppress your number. Not all carriers honor this request in the same way, and some prepaid or VoIP-based plans may ignore it entirely.
Carrier-Level Control 📞
Your carrier can also apply a permanent Caller ID block at the account level — this is separate from anything on your device. If you want persistent suppression that doesn't depend on your phone settings, contact your carrier directly to request it.
Some carriers offer this free; others charge a small monthly fee. This method tends to be more reliable across different devices, especially if you switch phones or use multiple SIMs.
Where Number Blocking Gets Complicated
VoIP and App-Based Calls
If you make calls through apps like WhatsApp, Google Voice, FaceTime Audio, Zoom Phone, or similar services, the *67 prefix and device settings generally don't apply. These apps use internet-based calling protocols (VoIP), and Caller ID behavior is controlled at the app level — if it's controllable at all.
Google Voice, for example, has its own anonymous calling option within its settings. WhatsApp shows your account profile, not your phone number, to the recipient regardless.
Business Lines and PBX Systems
Calls made through a PBX or business phone system may display a main office number rather than your direct extension by default. Suppressing or changing that display requires access to the PBX configuration — something typically managed by IT or your phone system administrator.
Recipient Call Settings
Some people and businesses set their phones to block anonymous calls — rejecting any call where the Caller ID is suppressed. If you hear a message like "This party does not accept calls from blocked numbers," the recipient's phone or carrier is filtering out private numbers. Your call won't go through in that case.
What Doesn't Change When You Block Your Number 🔒
A few things remain constant regardless of suppression settings:
- Emergency services (911) always receive your number
- Your carrier always has a record of your calls
- Toll-free numbers (1-800, 1-888, etc.) often use services that can unmask suppressed numbers
- Call detail records stored by carriers include your actual number regardless of what the recipient sees
Caller ID suppression affects what's displayed to the recipient — it doesn't make your call invisible at the network level.
Variables That Affect Which Method Works for You
The right approach depends on factors specific to your situation:
- How often you need suppression — occasional per-call use versus always-private calling
- Your device and OS version — menu paths differ between manufacturers and software versions
- Your carrier and plan type — postpaid, prepaid, and VoIP-based plans handle suppression differently
- Whether you use a smartphone or VoIP service as your primary calling method
- Whether recipients tend to block anonymous calls, which would make suppression counterproductive
The mechanics are consistent enough that the steps above will get most people there. But how reliably suppression works — and whether it's even the right approach — comes down to your specific phone, plan, and calling habits.