The fastest way to block SMS depends on your phone type

On an iPhone, open the Messages app, find the conversation you want to block, swipe left on it, tap the trash icon, then tap "Delete and Block." On an Android phone, open Messages (or your default SMS app), long-press the conversation, tap the three-dot menu, and select "Block." Both methods stop that sender from reaching you by text, and you won't see their messages in your inbox.

If you want to block before a message arrives — because you're getting spam texts from a number you've never seen — the process is the same: find any message from that number (even if it's just one) and block it using the steps above. You can also block a contact directly from your Contacts app on either phone type, which prevents them from calling or texting you.

These built-in blocking tools work for regular phone numbers. If you're getting texts from email addresses or apps that send SMS-like messages, you may need a different approach, which we cover below.

Key Takeaways

  • iPhone and Android both have free built-in blocking tools in their Messages apps that stop texts from reaching your inbox.
  • Blocking a number prevents that sender from texting you, calling you, and seeing your read receipts, but they won't receive a notification that you blocked them.
  • Spam texts from unknown numbers can be reported to your carrier (AT&T, Verizon, T-Mobile, etc.) to help protect other customers.
  • Third-party apps like TrueCaller or RoboKiller can filter spam texts automatically, but they require permission to read your messages.
  • If you're being harassed or threatened by text, save the messages and report them to local police in addition to blocking the number.

What happens when you block a number

When you block someone on iPhone or Android, their texts don't reach your phone at all — they go nowhere and you see nothing. The blocked sender doesn't get a delivery confirmation, and they won't know for certain that you blocked them (though they may suspect it if their messages never get responses). You also won't see their calls, FaceTime requests, or iMessage notifications.

Blocking is not the same as deleting a conversation. If you delete a thread without blocking, future messages from that number will still come through. If you block without deleting, the old conversation stays in your phone but you won't receive new messages from them. Most people do both: delete the old thread and then block the number.

One important limit: blocking only works on your phone. If someone texts you from a different number, blocking the first number won't stop the new one. Spammers and harassers sometimes use multiple numbers, so you may need to block several in a row.

Reporting spam texts to your carrier

Your phone company — AT&T, Verizon, T-Mobile, or another carrier — wants to know about spam texts because they affect all their customers. Most carriers let you forward spam texts to a short code (usually 7726, which spells SPAM) at no cost. On iPhone, you can also report a message as junk directly in the Messages app by swiping left and tapping "Report Junk."

When you report spam to your carrier, you're adding data to their spam-detection systems. This helps them block similar messages for everyone else on their network. It doesn't remove the message from your phone, but it does help prevent future spam from that source.

If you're getting a high volume of spam texts (more than a few per day), your carrier may be able to add a filter to your account. Call their customer service line and ask about spam-blocking options — some carriers offer this for free, while others charge a small monthly fee.

Using third-party filtering apps

Apps like TrueCaller, RoboKiller, and your carrier's own spam-blocking app (Verizon Call Filter, AT&T Call Protect, T-Mobile Scam Shield) can automatically filter spam texts before they reach your inbox. These apps work by comparing incoming messages against databases of known spam numbers and patterns. Some are free; others charge a monthly subscription for advanced features.

The trade-off with third-party apps is access: they need permission to read your text messages in order to filter them. Before you install one, check what permissions it's asking for. If an app wants access to your contacts, location, or photos in addition to messages, that's a sign to read the privacy policy carefully or choose a different app. Your carrier's own app is usually the safest choice because your carrier already has access to your phone number and billing information.

Third-party apps work best for high-volume spam. If you're getting only a few unwanted texts, blocking individual numbers is simpler and doesn't require giving another company access to your messages.

Blocking texts from email addresses and apps

Some services send messages that look like texts but actually come from email addresses or app servers. Gmail alerts, banking notifications, and two-factor authentication codes sometimes arrive this way. If you want to block these, the process depends on the source.

For legitimate services you signed up for (like bank alerts), the best approach is to log into your account on that service's website and turn off notifications in your settings. For unwanted messages from apps or services, you may not have a direct block option. Instead, you can mark the message as spam or junk, which trains your phone's filter to catch similar messages in the future.

If you're receiving unwanted messages from a specific app (like a dating app or social platform), check whether that app has a block or mute feature within the app itself. Many do, and blocking someone in the app prevents them from contacting you through that service.

When to involve law enforcement

Blocking is the right tool for spam and unwanted marketing texts. But if someone is threatening you, harassing you repeatedly, or sending messages that make you feel unsafe, blocking alone isn't enough. Save the messages (take screenshots if possible), note the dates and times, and report them to your local police department. Many departments have online reporting systems for harassment and threats.

If the harassment is coming from someone you know — an ex-partner, a coworker, a family member — law enforcement can help determine whether it crosses into stalking or harassment under your state's laws. If it's coming from a stranger, police can sometimes trace the number or work with your carrier to identify the sender.

You should block the number on your phone regardless, but the police report creates an official record in case the behavior escalates or you need a restraining order later.

Frequently Asked Questions

Can someone tell if I blocked them?

They won't get a notification, but they may figure it out if their messages never deliver and you stop responding. On iPhone, if they try to send you an iMessage, it will show as "Not Delivered" after a while, which can tip them off. The safest assumption is that a determined person will eventually realize they're blocked.

What if I block someone and then want to unblock them?

On iPhone, go to Settings > Messages > Blocked Contacts and swipe left on the name to unblock. On Android, open Messages, tap the three-dot menu, go to Settings > Blocked Numbers, and tap the X next to the number. Unblocking restores their ability to text and call you, but it doesn't restore old deleted messages.

Do I need to pay for spam blocking?

No. Your phone's built-in blocking is free, reporting to your carrier is free, and your carrier's own spam-blocking app is usually free (though some charge for premium versions). Third-party apps vary — some are free with ads, others charge monthly. You don't need to pay anything to block unwanted texts.

Will blocking stop two-factor authentication codes from my bank?

No. Two-factor codes come from your bank's official number, and blocking that number would prevent you from logging in. Only block numbers you're certain are spam or unwanted. If you're unsure whether a text is legitimate, call the company directly using the number on their official website or your statement.

What if the spam is coming from my own number?

This is a spoofing attack, where scammers fake the sender's number to make it look like it's coming from you. You can't block your own number, but you can report it to your carrier as spam. These messages are almost always phishing attempts or scams, so don't click any links or reply to them.