What blocking your number does

When you block your number before making a call, the person who receives it sees "Unknown," "Private," or "Blocked" instead of your phone number on their caller ID. The call still goes through — they can still answer and talk to you — but they cannot see who is calling them.

This is different from blocking a caller (where you prevent their calls from reaching you). You are controlling what information you send out, not what comes in.

Key Takeaways

  • You can block your number on a single call by dialing *67 before the phone number on most landlines and cell phones in the United States.
  • Blocking works for outgoing calls only and does not hide your number from emergency services, toll-free numbers, or some businesses.
  • Your phone's settings menu usually has a permanent block option if you want to hide your number on every call you make.
  • The person you call cannot unblock your number on their end — blocking happens from your phone, not theirs.

Using *67 to block a single call

The simplest way to block your number for one call is to dial *67 before you enter the phone number. On most phones in the United States, this tells your carrier not to send your caller ID information to the person you are calling.

The steps are: pick up your phone, dial *67, then dial the full phone number (including area code) as you normally would. Press call. The recipient will see a blocked or private number instead of yours.

This works on most landlines and cell phones. It does not work on all calls — 911 and other emergency numbers always receive your real number, and many toll-free numbers (like customer service lines) are set up to bypass the block and see your number anyway.

Blocking your number permanently in your phone settings

If you want to hide your number on every call you make, you can change this in your phone's settings instead of dialing *67 each time.

On an iPhone, go to Settings, then Phone, then Show My Caller ID. Turn this toggle off. Your number will be blocked on all outgoing calls unless you turn it back on.

On an Android phone, open the Phone app, tap the three-dot menu, go to Settings, then Call Settings, then Additional Settings, then Caller ID. Select "Hide Number" or "Private Number" depending on your phone model and carrier. The exact path varies by manufacturer and carrier, so if you cannot find it, search your phone's help for "hide caller ID" or contact your carrier.

What happens when you block your number

The person you call sees "Unknown," "Private," "Blocked," or a similar message on their caller ID instead of your name and number. They can still answer the call and hear you. You can still hear them. The conversation works exactly as a normal call would.

Some phones and services let the recipient leave you a voicemail, and some do not — it depends on their phone settings and carrier. If they do not answer, your call may go to their voicemail, or it may be rejected automatically because they have set their phone to reject blocked calls.

When blocking does not work

Emergency calls (911, poison control, and similar numbers) always receive your real number and location, even if you dial *67. This is a legal requirement so emergency responders can reach you if the call disconnects.

Many toll-free numbers and business lines are set up to see through caller ID blocks. Banks, government offices, and customer service departments often have systems that bypass the block so they can identify who is calling them. If you call a toll-free number and the block does not work, this is why.

Some carriers also allow customers to pay for a service that unblocks all incoming calls, so a recipient might see your number even if you blocked it — though this is uncommon.

The difference between blocking and other privacy options

Blocking your number is not the same as using a VoIP service, a second phone number app, or a burner phone. Those options give you a different number to call from instead of hiding your real number. Blocking hides your real number but does not change who you are calling from.

It is also not the same as blocking a caller on your own phone. When you block a caller, you prevent their calls and texts from reaching you. When you block your number, you prevent your number from reaching them.

Why someone might block their number

People block their numbers for many reasons: to avoid unwanted callbacks, to keep their personal number private when calling a business, to reach someone who may not answer an unknown number, or to maintain privacy in certain situations. There is nothing illegal about blocking your number for a regular call.

However, repeatedly calling someone and blocking your number to harass them is illegal in most places. If you are calling to threaten, intimidate, or repeatedly contact someone against their wishes, the blocking does not protect you from criminal charges.

Frequently Asked Questions

Can the person I call find out my number if I block it?

Not through normal caller ID. If they have special unblocking services or if you call a business with advanced systems, they might see it. If you leave a voicemail, they cannot hear your number from the message itself, but some voicemail systems show the number separately. Emergency services always see your real number.

Does *67 work on cell phones and landlines?

Yes, *67 works on most cell phones and landlines in the United States. Some carriers and some countries use different codes. If *67 does not work on your phone, contact your carrier to ask what code they use or whether they offer a caller ID blocking service.

What if I block my number and the person does not answer?

The call goes to their voicemail like any other unanswered call. They will see a missed call from a blocked or unknown number. Some people automatically reject calls from blocked numbers, so your call might not ring through at all.

Can I unblock my number after I have already called someone?

No. Once the call is made with your number blocked, the recipient sees it as blocked. You cannot change what they saw after the fact. If you need them to have your real number, you would need to call them again without blocking.

Is it illegal to block my number?

No, blocking your number is legal. Using it to harass, threaten, or repeatedly contact someone against their wishes is illegal. Using it for legitimate privacy reasons — calling a business, reaching someone who screens calls, protecting your personal number — is not.