The fastest way depends on your phone type and what you're blocking

Most phones let you block calls directly from the phone app or settings without installing anything extra. On iPhone, you open the Phone app, find the number in your recent calls or voicemail, tap the info icon, and select "Block this Caller." On Android, the steps are similar: open Phone, long-press the number, and choose "Block number." Both phones also let you block unknown or private numbers entirely through settings, which stops most spam calls before they ring.

If you want to block calls before they reach your phone at all, your phone carrier (Verizon, AT&T, T-Mobile, or another provider) offers call-blocking tools. These work at the network level, meaning the call never gets to your device. Most carriers offer a basic version free and a more advanced version for a monthly fee. The paid versions typically filter more aggressively and let you create custom block lists.

Key Takeaways

  • Your phone's built-in block feature stops calls from a specific number, but you have to add each one manually.
  • Blocking "unknown" or "private" numbers in your phone settings stops most spam calls, though it may also block legitimate callers who hide their number.
  • Your phone carrier offers network-level blocking that stops calls before they reach your phone, with free and paid options.
  • Third-party apps like RoboKiller or Nomorobo add extra filtering, but they work best alongside your phone's built-in tools, not instead of them.

Blocking a single number on iPhone

Open the Phone app and go to the Recents tab. Find the number you want to block, tap the circle with an "i" next to it, scroll down, and tap "Block this Caller." The number is now blocked — that person's calls will go straight to voicemail and you won't see a notification.

You can also block from a contact card. Open Contacts, find the person, tap "Edit," scroll to the bottom, and tap "Block this Caller." If you want to unblock later, go to Settings > Phone > Blocked Contacts, find the number, and tap "Unblock."

Blocking a single number on Android

Open the Phone app and go to Recents. Long-press the number you want to block, then tap "Block number" or "Block/report spam" (the exact wording varies by phone maker). The call will be silenced and sent to voicemail.

To unblock, go back to Recents, long-press the number again, and choose "Unblock." Some Android phones also let you block from Contacts by opening the contact, tapping the menu (three dots), and selecting "Block number."

Blocking unknown or private numbers

On iPhone: Go to Settings > Phone > Silence Unknown Callers. This sends any call from a number not in your contacts straight to voicemail. You won't hear it ring, but the call will still appear in your voicemail and recent calls. This is the single most effective way to stop spam, because most spam calls use random or spoofed numbers.

On Android: Go to Settings > Apps > Phone > Permissions > Call logs, then look for "Block unknown" or "Spam protection" (exact location varies by manufacturer). Some Android phones have this under Settings > Call settings > Block numbers. If you don't see it, your phone maker may not offer this feature — in that case, a third-party app is your next option.

The trade-off: legitimate callers who block their number (some businesses, hospitals, and government offices do this) will also go to voicemail. If you're expecting a call from someone who might hide their number, turn this off temporarily.

Using your carrier's call-blocking service

Verizon offers Call Filter free (basic spam detection) and Call Filter Pro for a monthly fee. AT&T offers Call Protect free and Call Protect Plus for a fee. T-Mobile offers Scam Shield free and Scam Shield Premium for a fee. These services block known spam numbers at the network level before the call reaches your phone.

To set up your carrier's service, go to your carrier's website or app and look for the call-blocking option. You'll usually see a toggle to turn it on. The free versions block obvious spam; the paid versions add features like a personal block list, reverse lookup, and more aggressive filtering. Check your carrier's website for current pricing, as it varies.

Network-level blocking is more effective than phone-level blocking because it stops the call before it uses your phone's resources. However, it relies on the carrier's database of known spam numbers, so new spam numbers may still get through until the carrier adds them.

Using third-party call-blocking apps

Apps like RoboKiller, Nomorobo, and Truecaller add an extra layer of filtering on top of your phone's built-in tools. They use databases of known spam numbers and machine learning to identify likely spam calls. Some apps also let you set custom rules — for example, "block all calls from numbers with this area code" or "allow calls only from contacts."

Most third-party apps require a subscription (typically $3 to $10 per month) after a free trial period. They work best on Android, where they have deeper access to your phone's call system. On iPhone, they're more limited because Apple restricts how much access third-party apps have to incoming calls.

Before paying for an app, try your phone's built-in blocking and your carrier's service first. Many people find those two tools handle 80 to 90 percent of spam without needing a third-party app. If spam is still a major problem after a few weeks, then a paid app may be worth trying.

What happens when you block a number

When you block a number on your phone, that person's calls go straight to voicemail without ringing your phone. You won't see a notification, and the call won't appear in your recent calls list. However, they can still leave a voicemail, and you can still see it if you check your voicemail inbox.

The blocked person doesn't get a message saying they've been blocked. From their perspective, the call either rings and goes to voicemail (if your phone is off or busy) or goes straight to voicemail (if you've blocked them). They have no way to know for certain that they're blocked.

If you block someone and then change your mind, you can unblock them anytime. On iPhone, go to Settings > Phone > Blocked Contacts. On Android, go to Phone > Recents, long-press the number, and tap "Unblock."

Frequently Asked Questions

Can a blocked person text me or reach me another way?

Blocking only stops calls and voicemails. They can still send text messages, emails, or reach you through social media or other apps. If you need to block someone completely, you may need to block them in each app separately or adjust your privacy settings in those apps.

Will blocking stop robocalls and spam?

Blocking one number at a time won't stop robocalls, because spam callers use different numbers each time. Blocking "unknown" numbers or using your carrier's spam filter will catch most robocalls. If robocalls are frequent, your carrier's paid service or a third-party app may help, but no tool stops all of them.

Does the blocked person know I blocked them?

No. They'll hear the phone ring and go to voicemail, just like when someone doesn't answer. They won't receive a notification or message saying they've been blocked. The only way they'd know is if you told them or if they tried multiple times and noticed a pattern.

Can I block calls from a specific area code?

Your phone's built-in tools don't let you block by area code — you have to block individual numbers. Some third-party apps like RoboKiller let you create rules for area codes, but this requires a paid subscription. Your carrier's paid call-blocking service may also offer this feature.

What if I accidentally block someone I know?

You can unblock them anytime. On iPhone, go to Settings > Phone > Blocked Contacts, find the number, and tap "Unblock." On Android, open Phone, go to Recents, long-press the number, and tap "Unblock." They'll be able to reach you when ready after you unblock them.