How to Block Your Number When Making a Call

Blocking your number before making a call is one of the most straightforward privacy tools available on any phone — but the method, reliability, and limitations vary depending on your carrier, device, and the network on the other end. Here's what you need to know about how it actually works.

What "Blocking Your Number" Actually Does

When you block your number, you're suppressing your Caller ID — the signal that tells the recipient's phone who is calling. Instead of your number appearing on their screen, they typically see "No Caller ID," "Private Number," or "Unknown."

This works through a standard telephony feature called CLIR (Calling Line Identification Restriction). When activated, your phone instructs the carrier network not to pass your number along to the receiving end. It's a legitimate, widely supported feature built into the global phone network — not a workaround or hack.

Important to understand: blocking your number hides it from the person you're calling, not from your carrier. Your carrier always knows the originating number, and emergency services (like 911 in the US) can also access it regardless of suppression settings.

The Most Common Methods

Per-Call Blocking with a Prefix Code 📞

The most universal method is dialing a prefix code before the number you're calling:

• United States & Canada: Dial *67 before the number (e.g., *67-555-867-5309)
• United Kingdom: Dial 141 before the number
• Australia: Dial 1831 before the number
• Ireland: Dial 141 before the number
• Many EU countries: Dial #31# before the number

This suppresses your Caller ID for that single call only. The next call you make goes out with your number visible again unless you repeat the prefix.

Permanent Caller ID Blocking Through Your Carrier

Most carriers offer account-level Caller ID blocking, which hides your number on every outgoing call automatically. This is typically activated by:

• Calling your carrier's customer service line
• Logging into your account settings online or in the carrier's app
• Requesting it through a retail store

When permanent blocking is enabled, you can temporarily unblock your number for a specific call by dialing *82 before the number (US/Canada). This is the reverse of *67 — it lifts the block just for that one call.

Blocking via iPhone Settings

On iPhone, you can toggle Caller ID off at the system level:

1. Open Settings
2. Tap Phone
3. Tap Show My Caller ID
4. Toggle it off

This applies to all calls made through the native Phone app. The setting persists until you change it back. Note that this goes through your carrier — it sends a CLIR instruction — so the actual behavior depends on your carrier's support for the feature.

Blocking via Android Settings

Android varies by manufacturer and carrier, but the general path is:

1. Open the Phone app
2. Tap the three-dot menu or Settings
3. Look for Calls, then Additional Settings or More Settings
4. Tap Caller ID and select Hide Number

Some Android devices on certain carriers gray this option out or remove it entirely, meaning the carrier doesn't support changing it at the device level. In those cases, the *67 prefix method still works.

What Affects Whether It Works

Blocking your number isn't guaranteed to behave identically in every situation. Several variables matter:

One particularly relevant variable: many people and businesses now automatically reject calls from blocked numbers. Spam filters and call-screening tools treat "No Caller ID" calls with high suspicion. If your goal is to reach someone rather than avoid identification for privacy reasons, a blocked number may simply go unanswered or to voicemail.

VoIP and App-Based Calls 🔒

Apps like WhatsApp, FaceTime, Signal, and Telegram work differently. These calls are routed over the internet, not the traditional phone network. The recipient typically sees your account name or phone number as registered in the app — you can't apply *67 to a WhatsApp call, for instance.

Google Voice is a notable exception: it provides a separate number you can use for outbound calls, effectively masking your personal number by design — without suppressing Caller ID, just replacing it.

The Variables That Shape Your Situation

How well call blocking works for you depends on several intersecting factors:

• Your carrier — and whether they support account-level CLIR
• Your device OS and version — which affects where the setting lives and whether it's accessible
• The type of call you're making — traditional cellular, VoIP, or app-based
• Your reason for blocking — one-off privacy vs. habitual use vs. professional context
• Who you're calling — individuals vs. businesses with call-screening infrastructure

The method that's most practical for someone making occasional private calls differs from someone who needs consistent number masking across devices and call types. And the approach that works seamlessly on one carrier or device may behave unexpectedly on another.