What blocking a phone number actually does
Blocking a phone number stops calls and text messages from that number from reaching you. When someone calls a blocked number, they typically hear a message saying the call cannot go through, or the call fails silently — they may not know they were blocked. Text messages from blocked numbers usually disappear before you see them, though the behavior varies slightly by phone type and carrier.
Blocking is different from ignoring a call in the moment. When you ignore a call, it still rings and you can see who called. When you block a number, the call never reaches your phone at all. You also won't see missed call notifications from blocked numbers, though most phones let you check a blocked list if you need to see who tried to contact you.
The block stays in place until you remove it. You can unblock a number at any time, and doing so takes about 30 seconds. Blocking one number does not affect your ability to receive calls from anyone else.
Key Takeaways
- On iPhone, open the contact, scroll to the bottom, and tap Block This Caller; on Android, open the contact and tap Block Number.
- You can also block a number directly from a missed call or text message without saving it as a contact first.
- Blocked callers will not hear a ring — the call fails on their end, though they may not know why.
- You can view your blocked list anytime and unblock a number in seconds if you change your mind.
- Blocking works only on your device; the person can still reach you from a different phone number unless you block that one too.
How to block a number on iPhone
Open the Phone app and go to Recents. Find the number you want to block, tap the information icon (a small circle with an "i" inside), and scroll to the bottom of the screen. Tap Block This Caller, then confirm by tapping Block Contact.
If the number is already saved in your Contacts, you can open the contact card instead. Scroll all the way to the bottom and tap Block This Caller. The process is the same either way.
You can also block a number from a text message. Open Messages, find the conversation, tap Edit in the upper left, select the conversation, and tap Delete. Then open the conversation again (it will still be there), tap the contact name at the top, and tap Block This Caller.
To see your blocked list, open Settings, tap Phone, and scroll down to Blocked Contacts. You will see every number you have blocked. To unblock someone, swipe left on their name and tap Unblock.
How to block a number on Android
Open the Phone app and go to Recents or Call History. Press and hold the number you want to block until a menu appears. Tap Block Number or Block Contact (the exact wording depends on your phone model and Android version). Confirm the block if prompted.
If the number is saved in your Contacts, open the contact card and tap the three dots menu in the upper right. Select Block Number or Add to Block List. Some Android phones also let you tap a block icon directly from the contact card.
To block from a text message, open Messages, press and hold the conversation, and look for a Block option in the menu that appears. Not all Android phones show this option in Messages, so if you do not see it, use the Phone app method instead.
To view your blocked list, open the Phone app, tap the three dots menu, and select Settings or Blocked Numbers. The exact path varies by manufacturer — Samsung phones, Google Pixels, and other brands organize this slightly differently, but the option is always in the Phone app settings. To unblock, find the number in the list and tap Unblock.
Blocking a number you have not saved as a contact
You do not need to save a number in your contacts before blocking it. If a number calls you and you do not recognize it, you can block it directly from the missed call notification or from your call history.
On iPhone, go to Recents, find the number, tap the information icon, and block it. On Android, press and hold the number in your call history and select Block. The number will be blocked even though it was never in your contacts.
This is useful for spam calls or unknown numbers. You can block them when ready without having to create a contact entry first.
What the person calling will experience
When someone calls a number you have blocked, they will not hear a ring. Instead, the call will fail when ready or after one or two seconds. On their end, they may see a message like "Call Failed" or "The call cannot be completed as dialed." Some carriers show a generic busy signal.
The blocked caller will not receive a message saying they were blocked. They may assume your phone is off, you are out of service, or there is a network problem. There is no notification that tells them the block is intentional.
Text messages from blocked numbers behave differently depending on your phone. On iPhone, blocked texts are moved to a separate folder and you will not see notifications. On Android, blocked texts are usually deleted automatically, though some phones let you view them in a blocked messages folder if you dig into settings.
Blocking calls from unknown or private numbers
If you are receiving calls from numbers that show as "Unknown," "Private," or "No Caller ID," you cannot block those calls the same way because there is no specific number to block. Instead, you need to use a different feature.
On iPhone, go to Settings, tap Phone, and turn on Silence Unknown Callers. This sends any call from a number not in your contacts to voicemail. You will not see a notification, but the call is recorded and you can listen to the voicemail later.
On Android, open the Phone app, tap the three dots menu, go to Settings, and look for Call Screening, Spam Protection, or Block Unknown Callers (the name varies by phone). Turn this feature on. Some Android phones also let you use Google Call Screen, which answers unknown calls automatically and transcribes them so you can decide whether to pick up.
Unblocking a number and what happens after
To unblock a number, go to your blocked list (Settings > Phone > Blocked Contacts on iPhone, or Phone app > Settings > Blocked Numbers on Android), find the number, and tap Unblock. The process takes about 10 seconds.
Once you unblock a number, that person can call and text you normally again. You will see their calls in your recent list and receive text message notifications. Unblocking does not notify them that you have unblocked them — they will not know unless you tell them.
If you unblock a number by mistake, you can block it again when ready. There is no waiting period or limit to how many times you can block and unblock the same number.
Frequently Asked Questions
Can someone tell if I have blocked them?
Not directly. When they call, they will hear a busy signal or a call failure message, but they will not receive a notification saying they were blocked. However, if they call multiple times and always get the same failure, they may suspect you have blocked them.
If I block someone, can they still text me?
No. Blocking stops both calls and text messages. Text messages from blocked numbers will not reach your phone or show up in your messages app.
What happens to voicemails from blocked numbers?
Blocked callers cannot leave voicemails on most phones. When they call a blocked number, the call fails before reaching your voicemail system. Some carriers handle this differently, but the standard behavior is that no voicemail is recorded.
Can I block a number that keeps calling from different numbers?
You can block each number individually, but if someone is calling from many different numbers, blocking one at a time is not practical. Instead, use the Unknown Caller blocking feature (Silence Unknown Callers on iPhone, Call Screening on Android) to send all unrecognized numbers to voicemail at once.
Will blocking a number use up my phone's storage or slow it down?
No. Blocking a number takes almost no storage space and has no effect on your phone's speed. You can block hundreds of numbers without any performance impact.