The fastest way depends on your phone type

On an iPhone, open the Phone app, find the number in your recent calls or messages, tap the info icon (the small circle with an "i"), scroll down, and tap "Block this Caller." On Android, open the Phone app, long-press the number in your call history, and select "Block number" from the menu. Both phones also let you block directly from a text message: swipe left on iPhone or long-press on Android, then choose block.

If you do not remember the exact number, you can block it from your contacts list instead. Find the contact, open it, scroll to the bottom, and choose the block option. The blocked number will not be able to call or text you, and their calls will go straight to voicemail without your phone ringing.

Some carriers also offer blocking through their own apps or websites. Verizon has Call Filter, AT&T has Call Protect, and T-Mobile has Scam Shield. These work alongside your phone's built-in blocking and can catch spam before it reaches your device, though some features require a paid subscription.

Key Takeaways

  • iPhone users tap the info icon next to a number and select "Block this Caller"; Android users long-press the number and choose "Block number."
  • You can block directly from a recent call, a text message, or your contacts list without needing to remember the exact number.
  • Blocked callers will reach your voicemail, and you will not see their calls or texts in your phone's history.
  • Your carrier may offer additional blocking tools through apps like Verizon Call Filter or AT&T Call Protect, some of which cost extra.

What happens when you block a number

When you block a number on your phone, that caller cannot reach you through calls or text messages. Their calls go directly to your voicemail, but they will not hear a busy signal or a message saying they are blocked — the call simply does not ring through. They may not realize they have been blocked, since the experience is the same as calling someone who is not answering.

Text messages from a blocked number still arrive on your carrier's servers, but your phone does not display them. You will not see a notification, and the messages will not appear in your conversation threads. If you later unblock the number, older blocked messages will not suddenly appear — they are gone from your phone's view.

Blocking is local to your device. If someone calls you from a blocked number using a different phone, that call will go through normally. Similarly, if you get a new phone or switch devices, your block list does not transfer automatically — you will need to set up blocks again on the new device.

Blocking spam and unknown numbers

If you receive calls from numbers you do not recognize, most phones let you block them without adding them to your contacts first. On iPhone, go to Settings, then Phone, then Call Blocking & Identification, and toggle on "Silence Unknown Callers" — this sends all calls from numbers not in your contacts to voicemail. On Android, open the Phone app, tap More (three dots), go to Settings, then Blocked Numbers, and you can add numbers manually or enable spam filtering.

Carrier-level blocking catches more spam because it works before calls reach your phone. Verizon Call Filter identifies likely spam and either blocks it automatically or lets you review it first. AT&T Call Protect does similar filtering. T-Mobile Scam Shield includes a feature called "Scam Block" that stops known scam numbers from ringing through. These services vary by plan — some are free, others cost a few dollars per month.

If you are getting repeated calls from the same number, blocking it on your phone is the quickest fix. If you are getting spam from many different numbers, a carrier service or a third-party app like Nomorobo or RoboKiller may catch more of it, though these require setup and sometimes a subscription.

Unblocking a number if you change your mind

On iPhone, go to Settings, then Phone, then Blocked Contacts, and swipe left on the number you want to unblock. On Android, open the Phone app, tap More, go to Settings, then Blocked Numbers, find the number, and tap the minus sign or delete option next to it. Once unblocked, that person can call and text you normally again.

Unblocking does not restore old messages or calls that arrived while the number was blocked. If you want to see whether someone tried to reach you, you will need to ask them directly or check your voicemail if they left one.

When blocking is not enough

If someone is harassing you through multiple numbers, blocking each one individually becomes impractical. In that case, consider reporting the behavior to your carrier and to the Federal Trade Commission at reportfraud.ftc.gov. If the harassment involves threats or feels like stalking, contact your local police department — they can sometimes work with carriers to identify the person behind the calls.

If you are being contacted by a debt collector or creditor, blocking them may not stop the calls legally. The Fair Debt Collection Practices Act allows collectors to contact you, though you can send a written request to stop. Keep a copy of that letter for your records. If they continue after you have sent it, that is a violation you can report.

For workplace harassment or calls related to a legal matter, document the calls (write down the date, time, and number) before blocking. That record can be useful if you need to show a pattern to your employer, a lawyer, or law enforcement.

Third-party blocking apps and their trade-offs

Apps like Nomorobo, RoboKiller, and Truecaller offer blocking beyond what your phone's built-in tools provide. They maintain databases of known spam numbers and can block calls before they reach you. Some also let you set custom rules — for example, blocking all calls from certain area codes or allowing calls only from your contacts.

The trade-off is that these apps need permission to access your call history and contacts to work effectively. Before installing one, check what data it collects and how it uses that data. Read the privacy policy, not just the app store description. Some apps are free with ads; others charge a monthly fee for ad-free blocking or extra features.

Your phone's built-in blocking and your carrier's service handle most common spam without needing a third-party app. A third-party app makes sense if you are getting an unusually high volume of spam calls or if you want more control over which calls get through.

Frequently Asked Questions

Can someone tell if I have blocked them?

Not directly from your phone. When they call, it goes to voicemail without a busy signal or rejection message. They might suspect it if you never respond to calls or texts, but your phone does not send them a notification that they are blocked.

Will blocking stop text messages from a number?

Yes. Text messages from a blocked number will not appear on your phone or trigger a notification. You will not see them in your message threads, though the messages may still exist on your carrier's servers.

What is the difference between blocking and silencing unknown callers?

Blocking targets a specific number you have already heard from. Silencing unknown callers sends all calls from numbers not in your contacts to voicemail automatically. Silencing is broader but may cause you to miss legitimate calls from people you do not have saved.

Do I need to pay to block numbers on my phone?

No. Your phone's built-in blocking is free. Your carrier may offer additional blocking services for a fee, but basic blocking through your phone costs nothing.

If I block someone and then unblock them, will they know?

No. Unblocking is invisible to the other person. They will not receive a notification, and there is no record on their end that you blocked them.