The fastest way to block telemarketer calls
Most phones have a built-in block feature that works immediately. On iPhone, open the Phone app, find the number in your recent calls or voicemail, tap the info icon (circle with an "i"), scroll down, and tap "Block this Caller." On Android, open the Phone app, press and hold the number, and select "Block number." The call will go straight to voicemail from then on.
If you don't have the number saved, you can still block it the moment it rings. On iPhone, swipe the incoming call to the left and tap the circle with a line through it. On Android, tap the decline button, then choose "Block number" from the menu that appears. Both methods take about two seconds.
Blocking one number at a time works for calls you recognize, but most telemarketer calls come from different numbers each time. For that reason, you'll also want to turn on your phone's spam filter, which catches many of these calls before they reach you.
Key Takeaways
- Your phone's built-in block feature stops calls from a specific number instantly, but telemarketers often use different numbers each time they call.
- Turning on your phone's spam filter (available on both iPhone and Android) catches many telemarketer calls automatically without you having to block each one.
- The National Do Not Call Registry stops some telemarketer calls, though it does not cover charities, political organizations, or companies you've done business with recently.
- Third-party apps like Nomorobo, TrueCaller, and RoboKiller offer more aggressive filtering but require you to grant them access to your call history.
- Carriers like Verizon, AT&T, and T-Mobile offer spam-blocking tools, some free and some paid, that work across their networks.
Turn on your phone's built-in spam filter
Both iPhone and Android have spam detection that runs in the background. On iPhone, go to Settings, tap Phone, then turn on "Filter Unknown Callers." This sends calls from numbers not in your contacts to voicemail and marks them as spam. You can still see them in your voicemail list if you want to check later.
On Android, the method depends on your phone's manufacturer. On most phones, open the Phone app, tap the three-line menu, go to Settings, then turn on "Spam Protection" or "Call Screen." Google Pixel phones have a feature called "Call Screen" that answers suspected spam calls automatically and transcribes them so you can read what they're saying without picking up.
The spam filter is not perfect — some telemarketer calls still get through, and occasionally a real call gets marked as spam. But it catches enough that you'll notice a real difference in how many unwanted calls reach you.
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, 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 works for most telemarketing calls, but it has gaps. Charities, political organizations, surveys, and companies you've done business with in the past 18 months can still call you. Scammers ignore the registry entirely, which is why blocking and filtering are still necessary even after you register.
Once you register, your number stays on the list permanently. You don't have to renew it. If you change phone numbers, you'll need to register the new number separately.
Use a third-party call-blocking app
Nomorobo is free on both iPhone and Android. It uses a database of known spam numbers and blocks them before they ring your phone. You can also report numbers yourself, which feeds back into the database. The free version blocks most common telemarketer patterns; a paid version ($2 per month) adds extra features like call recording and detailed reports.
TrueCaller is free and works by checking incoming numbers against a crowd-sourced database of spam and scam numbers. It also shows you the caller's name and business even if they're not in your contacts. The trade-off is that TrueCaller needs access to your contacts and call history to work, which some people prefer not to grant.
RoboKiller uses artificial intelligence to learn what spam sounds like and blocks it automatically. The free version blocks calls; the paid version ($4 per month) adds call recording and the ability to send spam callers to a fake voicemail that wastes their time. Like TrueCaller, it requires access to your call data.
All three apps work alongside your phone's built-in filter. They don't replace it — they add another layer. If you install one, keep your phone's spam filter on as well.
Check your carrier's spam-blocking tools
Verizon offers Call Filter free to all customers. It identifies spam calls and blocks them automatically, or you can set it to send them to voicemail instead. Verizon also offers Call Filter Pro ($3 per month) with extra features like reverse phone lookup and the ability to block calls by category (like political calls or surveys).
AT&T provides Call Protect free to all customers. It works similarly to Verizon's Call Filter, identifying and blocking spam. AT&T also offers Call Protect Plus ($4 per month) with call recording and more detailed spam reports.
T-Mobile includes Scam Shield free for all customers. It blocks known spam numbers and warns you about suspected scams before you answer. T-Mobile also offers Scam Shield Pro ($3 per month) with call recording and the ability to block calls by type.
These tools work at the carrier level, which means they can see patterns across millions of calls, not just your phone. That makes them effective at catching new spam numbers quickly. You don't need to install an app — they work automatically once you turn them on in your account settings or through your carrier's app.
What to do if you've already given out your number
If you're getting calls from a specific company, you can ask them to stop. When they call, ask to speak to someone who handles do-not-call requests, or ask for the company's mailing address and send a written request. Keep a record of when you asked and who you spoke to — if they call again after 30 days, you have proof they violated the law.
If the calls are harassing or threatening, or if you suspect fraud, report them to the Federal Trade Commission at reportfraud.ftc.gov. The FTC doesn't investigate individual complaints, but it uses patterns from many reports to go after large scam operations.
Changing your phone number is a last resort and usually not necessary. Between your phone's spam filter, the Do Not Call Registry, and a third-party app if you want one, you can reduce unwanted calls to a manageable level without giving up your number.
Frequently Asked Questions
Why do telemarketers use different numbers each time?
They use software that generates or rotates through numbers to avoid being blocked. When you block one number, they call from another. This is why filtering by pattern (spam filter, third-party apps) works better than blocking individual numbers for telemarketer calls.
Will registering with the Do Not Call Registry stop all unwanted calls?
No. The registry stops most telemarketer calls, but charities, political groups, surveys, and companies you've done business with can still call. Scammers and illegal operations ignore it entirely. That's why you need filtering and blocking as well.
Do I need to pay for call blocking?
No. Your phone's built-in spam filter and the Do Not Call Registry are both free. Your carrier may also offer free spam blocking. Paid apps and carrier upgrades add features like call recording or more aggressive filtering, but they're optional.
Can I block calls from a specific area code?
Most phones don't have a built-in feature to block entire area codes, but some third-party apps like TrueCaller and RoboKiller let you block calls by category or pattern. If you're getting calls from a specific area code repeatedly, blocking individual numbers as they come in is usually faster than setting up category-based rules.
What if a real call gets blocked by my spam filter?
Check your voicemail — blocked calls go there. If someone important needs to reach you, ask them to call again or to text you instead. You can also turn off the spam filter temporarily if you're expecting a call from an unknown number, like a doctor's office or delivery service.