The fastest way to stop spam calls is to use your phone's built-in blocking tools

Most smartphones come with spam-blocking features already installed. On iPhone, you can turn on Filter Unknown Senders in the Phone app settings, which silences calls from numbers not in your contacts. On Android, Call Screen (Google Pixel phones) or Spam Protection (Samsung) does the same thing — it sends suspected spam calls straight to voicemail without ringing your phone.

These built-in tools work by comparing incoming calls against known spam databases that your phone manufacturer updates regularly. They catch the most common patterns: robocalls, spoofed numbers, and calls from numbers that have been reported by other users. Turning them on takes less than a minute and requires no subscription.

If your phone doesn't have a native spam filter, or if you want stronger protection, your mobile carrier likely offers a free or low-cost app. AT&T offers Call Protect, Verizon offers Call Filter, and T-Mobile offers Scam Shield. These apps block calls before they reach you and let you review blocked calls in a separate log if you need to check whether something legitimate was caught by mistake.

Key Takeaways

  • iPhone's Filter Unknown Senders and Android's Call Screen are free, built-in tools that silence calls from numbers not in your contacts.
  • Your mobile carrier offers free or paid spam-blocking apps that work better than built-in tools because they use larger spam databases.
  • You can manually block individual numbers in your Phone or Contacts app, which is useful for persistent callers but does not stop new spam numbers.
  • Never answer calls from unknown numbers, return calls to unknown numbers, or press buttons during a call — these actions confirm your number is active and lead to more spam.
  • Registering your number on the National Do Not Call Registry reduces telemarketing calls but does not stop robocalls or scams.

How to block individual numbers on your phone

If a specific number keeps calling you, you can block it directly in your phone's contacts or call history. On iPhone, open the Phone app, find the number in your recent calls, tap the information icon next to it, scroll down, and tap Block this Caller. On Android, open the Phone app, find the number, tap the three dots, and select Block number.

Blocking a single number stops that caller from reaching you, but it does not prevent new spam numbers from calling. Spammers use different numbers for each call, so blocking one number rarely solves the problem. This method works best for people you know — ex-partners, aggressive debt collectors, or businesses you no longer want to hear from.

If you block a number by mistake, you can unblock it the same way. On iPhone, go to Settings > Phone > Blocked Contacts and swipe left to unblock. On Android, open the Phone app, tap the three dots, go to Settings > Blocked numbers, and tap the X next to the number you want to unblock.

Using your carrier's spam-blocking app for stronger protection

Your mobile carrier's app blocks more spam than your phone's built-in tools because it has access to a larger database of known spam numbers and patterns. AT&T Call Protect, Verizon Call Filter, and T-Mobile Scam Shield all work similarly: they screen calls before they ring your phone and log blocked calls so you can review them later.

Most carriers offer a free version of their app that blocks obvious spam. The paid versions (usually $3 to $5 per month) add features like reverse phone lookup, spam risk warnings before you answer, and the ability to block calls based on keywords in the voicemail. For most people, the free version is enough.

To set up your carrier's app, read it from your phone's app store, sign in with your phone number, and follow the setup prompts. The app will ask permission to access your call history and contacts — you need to grant these permissions for it to work. Once activated, it runs in the background and requires no further action from you.

Why you should not answer or return unknown calls

When you answer a call from an unknown number, you confirm to the caller that your number is active and monitored by a real person. Spammers use this information to add your number to their calling lists and sell it to other scammers. Even if you hang up when ready, you have already confirmed your number works.

Returning a call to an unknown number is even riskier. Some scams work by calling you once and waiting for you to call back — the return call triggers a charge to your phone bill or connects you to a premium service. Others use the return call to record your voice, which they can then use to impersonate you or commit fraud.

If you are unsure whether a call is legitimate, let it go to voicemail. Real callers — your bank, your doctor, your utility company — will leave a message with a callback number. You can then call that number back using the phone number on your bill or statement, which ensures you are calling the real organization and not a spoofed number.

Registering on the National Do Not Call Registry

The National Do Not Call Registry is a list maintained by the Federal Trade Commission that tells telemarketers they cannot call your number. You can register your phone number for free at donotcall.gov or by calling 1-888-382-1222 from the phone you want to register.

Registration takes effect when ready and lasts for five years. After five years, you can re-register if you want to stay on the list. The registry reduces calls from legitimate telemarketing companies, but it does not stop robocalls, scams, or calls from charities and political organizations, which are exempt from the rule.

If you continue to receive telemarketing calls after registering, you can file a complaint on the FTC website. The FTC investigates patterns of violations but does not handle individual complaints. For persistent unwanted calls, your spam-blocking app or carrier will be more effective than the registry.

What to do if spam calls are coming from your own number

Spammers sometimes spoof your own phone number, which means calls appear to come from you. This is unsettling but not dangerous — you cannot be scammed by a call from your own number, and you do not need to do anything to stop it. The spoofing is random and usually stops after a few days.

If people are calling you back saying they received calls from your number, tell them it is spoofing and that you did not make the calls. You do not need to contact your carrier or file a report — spoofing is widespread and carriers are aware of it. Your spam-blocking app will catch most of these calls before they reach anyone.

Do not try to call back the numbers that appear to be calling from your number. These are not real calls from your phone — they are spoofed calls that happen to display your number on the recipient's caller ID. Calling back will only reach whoever the spammer was actually calling.

Why spam calls happen and how they find your number

Spam calls come from several sources. Some are robocalls from companies trying to sell you something — credit cards, home security systems, or car warranties. Others are scams designed to steal your money or personal information. Still others are from debt collectors, political campaigns, or charities.

Spammers get your number by buying lists from data brokers, scraping it from public websites, or using random number generators. If you have ever entered your phone number on a website, signed up for a service, or posted it publicly, it is likely in a database somewhere. Once your number is in one list, it spreads to others.

You cannot prevent spammers from getting your number, but you can prevent them from reaching you. Spam-blocking tools are the most effective defense because they work automatically and improve over time as they learn which numbers are spam.

Frequently Asked Questions

Will blocking spam calls stop them completely?

No. Spam-blocking tools catch most spam calls, but some will still get through because spammers use new numbers constantly. The goal is to reduce the volume to a manageable level, not to eliminate spam entirely. If you are receiving dozens of calls per day, your carrier's paid app may be more effective than the free version.

Can I block calls from a specific area code?

Most phones do not have a built-in feature to block entire area codes, but some carrier apps do. If your carrier's app offers this feature, you can enable it in the app settings. Be careful — legitimate calls from businesses, doctors, and banks may come from area codes you do not recognize.

What if a spam call pretends to be from my bank or the IRS?

Hang up when ready. Your bank and the IRS will never call you unexpectedly asking for personal information, passwords, or payment. If you are concerned about a real debt or account issue, hang up and call the organization directly using the number on your statement or bill.

Does Do Not Call registration really work?

It works for legitimate telemarketing companies, which are required to follow it. It does not work for robocalls, scams, charities, or political organizations. If you are receiving mostly robocalls or scams, your spam-blocking app will be more effective than the registry.

Can I report a spam number to my carrier?

Yes. Most carrier apps have a report button next to blocked calls. Reporting helps the carrier improve its spam database, but it does not result in action against the spammer. For scams involving money or fraud, you can also report to the FTC at reportfraud.ftc.gov.