What blocking your caller ID actually does

When you block your caller ID, the person you call sees "Unknown," "Private," or "Blocked" instead of your phone number on their screen. Your call still goes through — they can still answer and talk to you. You are straightforward hiding the number that would normally appear on their end.

This is different from blocking a caller (where you prevent someone from reaching you). Blocking your caller ID is about what information you send out when you make the call.

Key Takeaways

  • Most phone carriers let you block your caller ID for all calls by dialing *67 before the number, or you can set it as a permanent default through your account settings.
  • Blocking your caller ID does not prevent the call from going through — the person can still answer, and emergency services can still see your real number.
  • Some businesses and government offices refuse to accept calls from blocked numbers, so you may need to unblock for certain calls.
  • Caller ID blocking is legal for personal use, but using it to harass, threaten, or defraud someone is a crime regardless of whether your number is hidden.

How to block your caller ID on a per-call basis

The simplest method works on almost any phone: dial *67 before the phone number you want to call. For example, if you are calling 555-123-4567, you would dial *67-555-123-4567 or *67 555-123-4567 (spacing varies by carrier). The person you reach will see a blocked or private number instead of yours.

This works on both landlines and mobile phones with most carriers in the United States. The block applies only to that single call — your next call will show your number again unless you dial *67 again.

Some carriers use different codes. If *67 does not work, contact your carrier directly to ask what code they use, or check your phone's settings menu under "Call Settings" or "Privacy."

How to block your caller ID for all calls

If you want your number hidden by default, you can set it in your account with your phone carrier. Log into your online account or call your carrier's customer service line and ask to enable "Caller ID Blocking" or "Anonymous Call Rejection" (the names vary). You will usually find this option under Privacy Settings or Call Settings.

Once enabled, every call you make will show as blocked unless you choose to unblock it for a specific call. To show your number on a single call when blocking is turned on, dial *82 before the number. This temporarily overrides your default setting for that one call.

Keep in mind that some businesses, government offices, and customer service lines will not accept calls from blocked numbers. If a call does not go through, you may need to turn off the blocking temporarily or use *82 to show your number for that particular call.

Why someone might block their caller ID

People block caller ID for many reasons. You might not want your number shared with a business you are calling for the first time. You might be calling from a shared phone and prefer not to give out your personal number. You might be concerned about your number being added to marketing lists or sold to data brokers.

Some people block their number when calling a business where they do not want their personal information recorded in the company's system. Others use it for privacy when calling from a workplace phone or a family member's phone.

What emergency services can and cannot see

Even if your caller ID is blocked, emergency services can still see your real phone number when you call 911. The blocking does not explore to emergency calls — the system overrides it automatically so that dispatchers can locate you if the call drops.

This is a legal requirement. No matter what privacy settings you have enabled, 911 always receives your actual number and location data (on mobile phones, this is approximate; on landlines, it is your registered address).

Legal limits on blocking your caller ID

Blocking your caller ID is legal for personal use. However, using a blocked number to harass, threaten, or defraud someone is a crime — the fact that your number is hidden does not change that. If you use caller ID blocking to make unwanted repeated calls, leave threatening messages, or commit fraud, you can be prosecuted.

Some states have additional rules. A few states require that you unblock your number if asked by law enforcement during an investigation. If you are being contacted by police or a court, do not assume that blocking your number protects you legally.

When blocking your caller ID might not work

Some phone systems are set up to reject or flag calls from blocked numbers. Banks, insurance companies, government offices, and many customer service lines often will not accept anonymous calls. If you call and the line disconnects or you get a message saying the call cannot be completed, the business may be rejecting blocked calls.

In these cases, you have two options: call back without blocking your number, or contact the business ahead of time through their website or a published phone number to ask how to reach them privately. Some businesses have separate processes for people who want to keep their number private.

Frequently Asked Questions

Can someone trace my number if I block my caller ID?

Not through normal means. A blocked number cannot be traced by the person receiving the call. However, law enforcement can subpoena phone records from your carrier to identify you if there is an active investigation. Blocking your number does not make you anonymous to your phone company or to the police.

Does blocking my caller ID stop my number from being sold to telemarketers?

No. Blocking your caller ID only hides your number from the person you are calling. Your carrier and the businesses you call still have your real number in their records. To reduce telemarketing calls, register with the National Do Not Call Registry at donotcall.gov or contact your carrier about call-filtering services.

What is the difference between *67 and *82?

*67 blocks your caller ID for a single call. *82 unblocks it for a single call if you have blocking turned on by default. They do the opposite thing: *67 hides your number when it would normally show, and *82 shows your number when it would normally be hidden.

Will blocking my caller ID work on text messages?

No. Caller ID blocking codes like *67 only work for voice calls. Text messages always show your phone number to the recipient. If you want to send a text without revealing your number, you would need to use a separate texting app or service, which is a different tool entirely.

Can my employer see that I blocked my caller ID on a work phone?

Possibly. If you are using a company phone, your employer may have access to call logs that show when a blocked call was made, even if they cannot see the number you called. Check your company's phone policy before blocking your caller ID on a work device — some employers prohibit it.