The fastest way to block a call depends on your phone type
Most phones let you block a number right from the call screen — when the call comes in, you reject it and choose "block this caller" or a similar option. On an iPhone, swipe the call away, tap the information icon, scroll down, and tap "Block this Caller". On Android, tap the decline button, then look for "Block number" or "Add to block list" in the call details. This stops that specific number from calling or texting you again.
If you want to block a number that already called you, open your recent calls list, find the number, and hold down on it (iPhone) or tap the three dots next to it (Android). The menu will show a block option. You can also block numbers from text messages the same way — find the conversation, tap and hold, and select block.
The drawback of blocking individual numbers is that it only stops one caller. If you get calls from many different numbers, or from numbers that change slightly each time, you need a different approach.
Key Takeaways
- You can block a single number directly from your phone's call screen or recent calls list in under 30 seconds.
- iPhone and Android both have built-in blocking that stops calls and text messages from reaching you, with no app needed.
- If you get calls from many numbers or spoofed numbers that change, your phone carrier offers free tools to filter them before they reach you.
- Do Not Call registries and reporting spam calls to your carrier help reduce unwanted calls across your network, though they take weeks to work.
- Third-party apps can add extra filtering layers, but your phone's built-in tools handle most common cases without cost.
Use your phone carrier's call filtering service
Your phone company — whether it's Verizon, AT&T, T-Mobile, or another carrier — offers free or low-cost tools that filter calls before they reach your phone. These work differently than blocking a single number: they screen incoming calls against databases of known spam and robocall numbers, and they can stop calls from numbers that don't match real caller ID patterns.
Verizon offers Call Filter for free (with limited features) or Call Filter Pro for a monthly fee. AT&T has Call Protect, also free with a paid tier. T-Mobile includes Scam Shield at no cost. To turn these on, log into your carrier's account online or call customer service. The setup takes a few minutes, and once it's active, many unwanted calls are blocked automatically before your phone even rings.
These carrier tools are more effective than blocking individual numbers because they catch calls from numbers you've never seen before. They also let you see a list of blocked calls in your phone's app, so you can review what was stopped.
Register with the National Do Not Call Registry
The National Do Not Call Registry is a free list maintained by the Federal Trade Commission. When you add your number to it, telemarketers are legally required to stop calling you within 31 days. You can register online at donotcall.gov or by calling 1-888-382-1222 from the phone you want to register.
The registry does not stop all unwanted calls — it does not cover charities, political organizations, surveys, or companies you've done business with in the past 18 months. It also does not stop scammers or robocalls from people breaking the law. But it does reduce legitimate telemarketing calls, and it is free and takes less than five minutes.
Your number stays on the registry for life. You do not have to renew it. If you stop receiving calls from a telemarketer after registering, you can report them to the FTC at reportfraud.ftc.gov.
Report spam calls to your carrier and the FTC
When you get a spam or robocall, reporting it helps your carrier improve its filtering and helps the FTC track patterns. On most phones, you can report a call directly from your recent calls list. On iPhone, tap the information icon next to the number and scroll to "Report as Junk". On Android, tap the three dots and look for "Report spam" or "Report as spam".
You can also report calls to your carrier's fraud department. Verizon, AT&T, and T-Mobile all have online forms or phone numbers for reporting spam. When you report, include the number that called, the date and time, and what the call was about if you know it. Carriers use this data to update their blocking lists, so newer spam numbers get caught faster.
For serious scams — calls threatening arrest, demanding money, or claiming to be from the IRS or Social Security — report them to the FTC at reportfraud.ftc.gov. The FTC shares this information with law enforcement and uses it to shut down scam operations.
Consider a third-party call-blocking app
Apps like RoboKiller, Nomorobo, and Truecaller add an extra layer of filtering beyond what your phone and carrier provide. These apps use artificial intelligence and community reports to identify and block spam calls. Some also let you set custom rules — for example, blocking all calls from unknown numbers, or allowing calls only from contacts in your phone.
Most third-party apps are free with limited features or cost a few dollars per month for full access. Before you read one, check whether your carrier's free tool is already handling your problem — many people find that Verizon Call Filter, AT&T Call Protect, or T-Mobile Scam Shield is enough. If you still get many unwanted calls after using your carrier's tool, a third-party app may help.
Be cautious about apps that claim to block all calls or may provide no spam will ever reach you. No tool is perfect, and some apps ask for permissions they do not need (like access to your contacts or location). Read the reviews and check what permissions the app requests before installing it.
What to do if a blocked caller tries to reach you
When you block a number on your phone, that caller cannot reach you by phone or text. Their calls go to voicemail (or are rejected silently, depending on your settings), and their text messages do not appear in your messages. They will not know they are blocked — they may think you are not answering, or they may get a generic message from your carrier.
If a blocked caller uses a different number to reach you, you will see the call come through. You can block that new number the same way. If someone is harassing you from multiple numbers, your carrier's call filtering tool is more effective than blocking individual numbers, because it can catch patterns across many numbers.
If you believe you are being harassed or threatened, save the numbers and dates of the calls, and report them to your local police department. You can also file a complaint with the FTC at reportfraud.ftc.gov.
Unblock a number if you change your mind
On iPhone, go to Settings, tap Phone, tap Call Blocking & Identification, and you will see a list of blocked numbers. Tap "Edit" in the top left, then tap the minus sign next to a number to unblock it. On Android, open the Phone app, tap the three dots (or menu icon), go to Settings, tap Blocked Numbers, find the number, and tap the X or trash icon next to it.
If you blocked someone through your carrier's app (like Verizon Call Filter), you unblock them in that app, not in your phone's settings. Open the app, find the blocked calls list, and look for an unblock or allow option.
Frequently Asked Questions
Can someone tell if I blocked them?
No. When you block a number, the caller does not receive a notification. Their call may go to voicemail, or they may hear a generic message from your carrier. They have no way to know for certain that you blocked them rather than straightforward not answering.
Will blocking a number stop them from texting me?
Yes. Blocking a number stops both calls and text messages from that number. Text messages from a blocked number do not appear in your messages app, and the sender does not know the message was blocked.
What is the difference between blocking and Do Not Call?
Blocking stops one specific number from reaching you. Do Not Call tells telemarketers they are not allowed to call you at all. Do Not Call takes 31 days to work and does not stop scammers or calls from companies you have done business with. Blocking works when ready but only stops the numbers you choose.
Do I have to pay for call filtering?
No. Your phone carrier offers free call filtering — Verizon Call Filter, AT&T Call Protect, and T-Mobile Scam Shield are all free. They have paid versions with more features, but the free versions block most spam. Third-party apps may charge a fee, but your carrier's tool is usually enough.
Why do I still get spam calls after blocking numbers?
Spammers and robocallers use different numbers for each call, so blocking one number does not stop them from calling you from a new number. Your carrier's call filtering tool is more effective because it catches patterns across many numbers. If you still get many calls after turning on your carrier's filter, a third-party app may help, or the calls may be from scammers breaking the law.