The fastest way depends on your phone type

On most phones, you can block a number in seconds by opening the call log, finding the number you want to block, and selecting a block or report option. The exact steps differ between iPhone and Android, and some carriers offer additional blocking through their own apps or online accounts. You can also block numbers before they call you by adding them to a contacts list marked as blocked, or by using a third-party call-blocking app.

The method you choose matters because some approaches block only calls and texts from that number, while others also prevent the caller from leaving voicemails or seeing that you read their messages. If you are being harassed by many numbers or numbers that keep changing, a third-party app may work better than blocking one number at a time.

Key Takeaways

  • On iPhone, open the Phone app, find the number in your recent calls, swipe left, and tap Block This Caller; on Android, open the Phone app, long-press the number, and select Block.
  • Blocking a number stops calls and texts from reaching you, but the caller may still be able to leave voicemails unless your carrier offers a separate voicemail-blocking feature.
  • Your phone carrier (Verizon, AT&T, T-Mobile, etc.) may offer free or paid call-blocking services through their own apps or online account settings.
  • Third-party apps like Nomorobo, RoboKiller, and Truecaller can block calls from unknown numbers and spam patterns, but they require permission to access your call logs and contacts.
  • If you are being harassed or threatened, document the calls and contact local police; blocking alone does not stop someone determined to reach you through other means.

Blocking on iPhone

Open the Phone app and go to the Recents tab at the bottom. Find the number you want to block, tap the information icon (a small circle with an "i"), scroll down, and tap Block This Caller. The number is now blocked — the caller will not reach you, and their calls will not appear in your recent list.

If you want to block a number that is already in your Contacts, open Contacts, select the person, tap Edit, scroll to the bottom, and tap Block This Caller. You can also block a number from a text message by opening the conversation, tapping the contact name at the top, and selecting Block This Caller.

To see your list of blocked numbers, open Settings, go to Phone, and tap Blocked Contacts. You can unblock a number from this list by tapping Edit and then the minus sign next to the contact name.

Blocking on Android

Open the Phone app (the default calling app on your device). Go to the Recents or Call Log tab, long-press the number you want to block, and select Block or Block Number from the menu that appears. The exact wording depends on your phone manufacturer and Android version, but the option is always in this menu.

You can also block a number from a text message by opening the conversation, long-pressing the contact name, and selecting Block. If the number is already in your Contacts, open Contacts, select the person, tap the three-dot menu, and choose Block.

To see your blocked list, open the Phone app, tap the three-dot menu, and select Settings or Blocked Numbers. The exact path varies by manufacturer — Samsung phones may label it differently than Google Pixel phones — but the option is always in the Phone app settings.

Using your carrier's blocking service

Verizon, AT&T, T-Mobile, and other carriers offer their own call-blocking tools, separate from your phone's built-in blocking. These services often catch spam and robocalls before they reach your phone, not just block numbers you have already received.

Verizon offers Call Filter (free basic version, paid premium version with more features). AT&T offers Call Protect (free basic version, paid premium). T-Mobile offers Scam Shield (free basic version, paid premium). You can turn these on through your carrier's app or by logging into your online account. Some carriers also let you block numbers directly through their website.

The advantage of carrier blocking is that it works even if you change phones or switch to a new device, because the block is tied to your phone number, not your device. The disadvantage is that you have to manage blocks in two places — your phone and your carrier's app — if you want full coverage.

Third-party call-blocking apps

Apps like Nomorobo, RoboKiller, Truecaller, and Whoscall can block calls from numbers you have reported as spam, and they can also block calls from unknown numbers that match spam patterns. These apps work by comparing incoming calls against a database of known spam and scam numbers.

To use a third-party app, download it from the Google Play Store or Apple App Store, open it, and follow the setup steps. The app will ask permission to access your call logs, contacts, and sometimes your location. Once enabled, it runs in the background and blocks calls before they reach you.

The trade-off is that these apps collect data about your calls and contacts to improve their spam detection. Read the privacy policy before installing to understand what information the app collects and how it is used. Some apps are free with ads; others charge a monthly fee for ad-free blocking.

What blocking does and does not do

When you block a number, that caller cannot reach you by phone call or text message. Their calls go nowhere, and their texts do not appear in your message threads. However, blocking does not always stop voicemails — the caller may still be able to leave a message that appears in your voicemail inbox, depending on your carrier and phone settings.

Blocking also does not hide the fact that you have blocked them. Some callers will realize they are blocked when their calls go straight to voicemail every time, or when texts never deliver. If someone is determined to contact you, they can use a different phone number, email, or social media account.

If you are being harassed, threatened, or stalked, blocking is a useful first step, but it is not a complete solution. Document the calls and messages, and contact your local police department if the behavior is threatening or continues after you have blocked the number.

Blocking numbers you have never received a call from

You can block a number before it ever calls you by adding it to your contacts and marking it as blocked. On iPhone, create a new contact, enter the phone number, and tap Block This Caller before saving. On Android, create a new contact with the number, save it, then long-press it in your contacts list and select Block.

This approach is useful if you have a number you want to prevent from reaching you — for example, a business number you no longer want to hear from, or a number someone gave you that you do not want to accept calls from. The number will be blocked the moment it tries to call, even though you have never received a call from it before.

Frequently Asked Questions

Can someone tell if I have blocked them?

Not directly from your phone, but they may figure it out. If they call repeatedly and always reach voicemail, or if texts never show a delivery status, they may suspect they are blocked. Some people try calling from a different number to test whether they are blocked on the original number.

If I block a number, can they still leave voicemails?

It depends on your carrier and settings. On some carriers, blocked callers can still leave voicemails that go to your voicemail inbox. Check your carrier's website or call their customer service to see if they offer voicemail blocking as a separate feature, or ask how to prevent blocked callers from leaving messages.

What is the difference between blocking and reporting spam?

Blocking stops that specific number from reaching you. Reporting spam sends information about the number to your carrier or to the app's database, which helps protect other people from the same caller. Most apps let you do both at once — block the number and report it as spam.

Can I block a number that shows up as "Unknown" or "No Caller ID"?

You cannot block an unknown number directly because there is no number to block. However, you can use your phone's settings to silence calls from unknown numbers. On iPhone, go to Settings > Phone > Silence Unknown Callers. On Android, open the Phone app settings and look for an option to block unknown or private numbers.

Do I need to unblock a number if I want to contact them?

No. Blocking is one-way — it stops them from reaching you, but you can still call or text them. If you unblock a number, they can call you again. You only need to unblock if you want to receive calls and texts from that number again.