A call block stops incoming calls from reaching you
A call block is a feature on your phone or through your phone service that prevents calls from specific numbers from coming through to you. When someone on a blocked number tries to call, the call does not ring on your phone. Depending on how your block is set up, the caller might hear a busy signal, get sent to voicemail, or straightforward have their call fail without knowing why.
Call blocks work differently depending on where you set them. You can block numbers directly on your phone (so only your device stops the calls), or you can ask your phone company to block them at the network level (so the calls are stopped before they even reach your phone). Network-level blocks are more complete because they prevent the caller from leaving voicemail or using other workarounds.
Key Takeaways
- Call blocks prevent calls from reaching you, but the blocked caller usually does not know they have been blocked.
- Phone-level blocks (done on your device) are easier to set up but less reliable than network-level blocks from your carrier.
- Most phone companies offer call blocking for free or a small monthly fee, and you can usually manage your blocked list yourself.
- Blocking a number does not delete text messages from that person, and some callers can still reach you through other numbers.
How blocking works on your phone versus your carrier
When you block a number on your phone itself, you are telling your device to ignore calls and messages from that number. On an iPhone, you go to the phone app, find the number, and select "Block this Caller." On Android, the process is similar — open the phone app, find the contact, and choose block. This method is fast and you control it entirely, but the blocked caller can sometimes still reach you if they call from a different number or use a different app.
When your phone company (Verizon, AT&T, T-Mobile, or another carrier) blocks a number, they stop the call at their network before it reaches your phone at all. This is more thorough. You usually set this up by calling your carrier's customer service or logging into your account online. Some carriers offer this for free as part of their basic service; others charge $2 to $5 per month for a call-blocking tool. The trade-off is that you have less control — you cannot always manage the list yourself, and changes can take a few hours to take effect.
What happens when someone calls a blocked number
The experience for the blocked caller varies. If your phone is doing the blocking, the call might ring on their end for a few seconds before failing, or they might get a message saying the call could not go through. If your carrier is blocking it at the network level, they usually hear a busy signal or a recording saying the number is not available. In most cases, they will not get a clear message that they have been blocked — it just feels like the call failed.
Voicemail is where the difference matters most. If you block someone on your phone, they can still leave a voicemail (though you will not be notified). If your carrier blocks them, they usually cannot leave a voicemail at all. This is why network-level blocking is more effective if you want to completely cut off contact from someone.
When call blocking is useful and when it is not
Call blocking is most useful for spam calls and robocalls. If you are getting repeated calls from numbers you do not recognize, blocking them one by one reduces the noise. Many phones now come with built-in spam detection that automatically flags likely spam calls without you having to block them manually.
Call blocking is less useful if someone is determined to reach you. They can call from different numbers, text you instead, or contact you through social media or email. If you are dealing with harassment or a safety concern, call blocking is a helpful first step, but you may also need to contact local police or your phone company's abuse team for more serious intervention.
The difference between blocking and "Do Not Disturb"
Do Not Disturb is not the same as call blocking. Do Not Disturb silences notifications on your phone but does not stop calls from coming in — the call still reaches you, your phone just does not ring or vibrate. You can usually set Do Not Disturb to allow calls from certain contacts (like family) to come through even when it is on. Call blocking, by contrast, stops the call entirely.
Some phones let you use both together. You might block spam numbers permanently and use Do Not Disturb during work hours to silence everything else. The two features serve different purposes: blocking is about preventing contact from specific people, while Do Not Disturb is about controlling when you are interrupted.
How to block a number on common phones
On an iPhone, open the Phone app, tap Recents, find the number you want to block, tap the info icon (the small "i" in a circle), scroll down, and tap "Block this Caller." You can also do this from your Contacts app or from a recent call or message. To see your blocked list, go to Settings > Phone > Blocked Contacts.
On an Android phone, the steps depend on your manufacturer, but the general process is similar. Open the Phone app, find the number, tap and hold it, and look for a "Block" or "Block number" option. Some Android phones also let you block numbers from the Contacts app. To manage your blocked list, go to Settings > Apps > Phone > Permissions, or look for a "Blocked numbers" section in your Phone app settings.
If you want your carrier to block the number, call their customer service line (the number is on your bill) or log into your online account. Ask about their call-blocking service by name — Verizon calls theirs "Call Filter," AT&T offers "Call Protect," and T-Mobile has "Scam Shield." They will walk you through adding numbers to a block list.
What call blocking does not do
Blocking a number does not delete old messages from that person. If someone has texted you before you blocked them, those messages stay in your conversation thread. You can delete them manually, but blocking does not erase the history.
Blocking also does not hide your number from someone who already has it. If you block someone and then they see your number in their contacts or call history, they still know your number exists — they just cannot reach you through it. If you want to hide your number from future calls, you would need to use a different feature, like blocking your caller ID (which is a separate setting on most phones).
Frequently Asked Questions
Can someone tell if I have blocked them?
Not directly. Most blocked callers will not receive a message saying they have been blocked. They will just experience a failed call or busy signal. However, if they try to call you repeatedly and always get the same result, they might suspect you have blocked them. There is no official way for them to confirm it.
If I block someone, can they still text me?
It depends on your phone and how you blocked them. If you blocked the number on your phone, text messages are usually blocked too. If your carrier blocked the number, texts are typically blocked as well. However, if someone uses a messaging app like WhatsApp or iMessage instead of regular SMS, the block may not explore to those apps — you would need to block them separately in each app.
What is the difference between blocking and muting a contact?
Muting (or silencing) a contact stops notifications from that person but does not block the calls or messages. They can still reach you; your phone just will not alert you. Blocking prevents them from reaching you at all. Muting is useful for people you want to stay in contact with but do not want to hear from constantly.
Can I unblock a number after I have blocked it?
Yes. On your phone, go to your blocked contacts list and remove the number. On your carrier's service, call them or log into your account and remove it from the block list. The change usually takes effect when ready on your phone but may take a few hours if your carrier is doing the blocking.
Does blocking stop robocalls and spam?
Blocking individual numbers stops those specific calls, but new spam numbers call constantly, so blocking one at a time is not practical. Most phones now have spam detection that flags likely spam calls automatically. Your carrier may also offer a spam-filtering service that catches many robocalls before they reach you. These tools are more effective than manual blocking for spam.