The fastest way to block a telemarketer is to hang up and use your phone's built-in block feature

When a telemarketer calls, you do not have to listen. Most phones — whether iPhone, Android, or a landline through your provider — let you block the number when ready after the call ends. On an iPhone, open the recent call, tap the info icon, and select "Block this Caller". On Android, press and hold the number in your call log, then tap "Block number". For landlines, your phone company's website or a call to their customer service line will let you add numbers to a block list.

Blocking one number at a time works if you get calls from the same telemarketer repeatedly, but most telemarketing calls come from different numbers each time. That is why the real solution is to register your number on the National Do Not Call Registry and use your phone's spam-filtering tools together.

Key Takeaways

  • Register your phone number at donotcall.gov to tell telemarketers you do not want to hear from them — this is free and takes two minutes.
  • Turn on spam filtering in your phone's settings: iPhone has "Filter Unknown Senders" under Messages, and Android has "Spam and abuse" settings in the Phone app.
  • Block individual numbers right after a call ends using your phone's built-in block feature, which stops that specific number from reaching you again.
  • Some calls will still get through because telemarketers use spoofed numbers and new numbers constantly, so combining methods works better than any single one.

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, you are telling most telemarketing companies that you do not want sales calls. Registration is permanent — your number stays on the list even if you do not use it for a while, and you never have to renew it.

Go to donotcall.gov on a computer or phone and enter your number. You can also call 1-888-382-1222 from the phone you want to register. You will get a confirmation email or text within a few days. After that, telemarketers have 31 days to stop calling you. Some will ignore the registry, which is why blocking and filtering matter too.

The registry does not stop calls from charities, political organizations, surveys, or companies you have done business with in the past 18 months. It also does not stop debt collectors or scammers, who ignore the law anyway. But it does reduce the volume of unwanted sales calls most people receive.

Use your phone's built-in spam filter

Both iPhone and Android have spam-filtering tools that catch many telemarketing calls before they ring. On iPhone, go to Settings, then Messages, and turn on "Filter Unknown Senders". This sends texts from people not in your contacts to a separate tab. For calls, go to Settings, Phone, and turn on "Silence Unknown Callers" — unknown numbers will go straight to voicemail.

On Android, open the Phone app, tap the three-line menu, go to Settings, then Spam and abuse, and turn on "Filter spam calls". You can also turn on "See caller ID and spam" to see which calls the system thinks are spam before you answer. Some Android phones also let you block calls from numbers not in your contacts.

These filters are not perfect — they sometimes block legitimate calls, and some spam gets through — but they catch a large percentage of telemarketing calls without you having to do anything.

Block numbers one at a time after they call

When a telemarketer calls and you answer, hang up as soon as you realize it is a sales call. Then block the number right away. On iPhone, go to Recents, find the number, tap the info icon (a circle with an i), scroll down, and tap "Block this Caller". On Android, press and hold the number in your call log and tap "Block number".

This stops that specific number from calling you again, but telemarketers often use a different number for each call. They do this by spoofing — using software to make their call appear to come from a different number each time. So blocking individual numbers helps with repeat callers but will not stop new numbers from getting through.

Add numbers to your phone company's block list

If you have a landline or want an extra layer of blocking, your phone company offers a block list. Call your provider's customer service number (on your bill) and ask them to add numbers to your block list. Some providers let you do this online through your account. Verizon, AT&T, and other major carriers all offer this service, though some charge a small monthly fee for advanced call-blocking features.

Your phone company can block numbers at the network level, which means the call never reaches your phone at all. This is more powerful than blocking on your device, but it requires you to call or log in to your account each time you want to add a number.

Consider a third-party call-blocking app

Apps like Nomorobo, RoboKiller, and Truecaller use databases of known telemarketing and spam numbers to block calls automatically. Many of these apps are free or cost a few dollars per month. They work by checking incoming calls against their database and either blocking them or sending them to voicemail.

The advantage of a third-party app is that it updates its database constantly as new spam numbers appear. The disadvantage is that you are giving the app access to your call history and contacts. Read the privacy policy before installing any app, and stick with apps from companies with a clear privacy statement.

For most people, the combination of Do Not Call registration, your phone's built-in spam filter, and blocking individual numbers is enough. Third-party apps help if you still get a high volume of calls after using those tools.

What to do if a telemarketer ignores the Do Not Call Registry

If a company keeps calling after you have registered with the Do Not Call Registry, you can file a complaint at donotcall.gov. The FTC investigates patterns of violations, not individual calls, so one complaint may not result in action. But if many people complain about the same number, the FTC can fine the company or take legal action.

You can also hang up when ready and block the number. Do not engage with the caller or ask to be removed — telemarketers sometimes use your response to confirm your number is active, which can lead to more calls. Hanging up and blocking is faster and more effective.

Frequently Asked Questions

Will registering with Do Not Call stop all telemarketing calls?

No. The registry stops most legitimate telemarketing companies, but charities, political groups, surveys, and debt collectors are exempt. Scammers ignore the law entirely. Combining registration with spam filtering and blocking will reduce calls significantly, but some will still get through.

Can I block calls from a specific area code?

Your phone's built-in tools cannot block an entire area code, but some third-party apps can. However, blocking by area code risks blocking legitimate calls from businesses or family members in that area. It is better to block individual numbers or use spam filtering.

What if I accidentally block a number I need?

On iPhone, go to Settings, Phone, and tap "Blocked Contacts" to see your blocked list and unblock numbers. On Android, open the Phone app, tap the menu, go to Settings, Spam and abuse, then "Blocked numbers", and tap the X next to the number you want to unblock.

Do I have to pay to register with Do Not Call?

No. Registration at donotcall.gov and the phone line 1-888-382-1222 are both free. Do not pay anyone claiming to register you for a fee — the government service costs nothing.

Why do telemarketers use different numbers each time?

Telemarketers use spoofing software to make calls appear to come from different numbers. This defeats call-blocking because you cannot block a number you have never seen before. Spam filters work better against this tactic because they identify patterns in the calls themselves, not just the number.