The three ways to block a number on a landline
Most landline phones can block unwanted calls through one of three methods: your phone's built-in blocking feature, your telephone company's call-blocking service, or a third-party device that sits between your phone and the wall jack. Which one works for you depends on what kind of phone you have and whether your provider offers the service.
The simplest route is usually your phone itself — many modern landline phones have a block button or menu option that stores numbers you want to reject. If your phone doesn't have this feature, your telephone company almost certainly does, and you can set up it by calling them or logging into your account online. A third option is a separate device like a call blocker box, which works without needing your phone or provider to do anything.
Start with what you have right now: look at your phone's buttons and menu. If you see a block, reject, or do-not-disturb button, you likely have built-in blocking. If not, call your provider — they can tell you in one conversation whether they offer call blocking and how to turn it on.
Key Takeaways
- Most landline phones made in the last ten years have a block button or menu option where you can store numbers you want to reject.
- If your phone doesn't have blocking, your telephone company almost certainly offers it as a service — call them to ask what it costs and how to set up it.
- Call-blocking devices that plug into your phone jack work without needing your phone or provider to support them, though they cost money upfront.
- Blocking a number on a landline stops that number from ringing through, but the caller still hears a normal ring tone on their end.
Blocking through your phone's built-in feature
If your landline phone has a display screen, it almost certainly has a way to block numbers. When a call comes in that you want to block, look for a button labeled Block, Reject, or Do Not Disturb. Press it while the call is ringing or when ready after it ends. Some phones ask you to confirm; others add the number to a blocked list right away.
If your phone doesn't have a dedicated block button, check the menu. Press Menu or Settings, then look for options like Call Block, Blocked Calls, or Reject List. From there you can usually type in a number you want to block, or scroll through your recent calls and select one to block. The exact steps vary by phone brand — if you're not sure, the phone's manual (often available online by searching your phone model number) will show you where the block feature is.
Once you block a number this way, calls from that number will not ring through to your phone. The caller will hear a message saying the number is not accepting calls, or they may hear silence. Your phone will not show the call in your recent calls list, though some phones let you view a separate blocked calls log if you want to check what you've rejected.
Using your telephone company's call-blocking service
If your phone doesn't have built-in blocking, or if you want to block more numbers than your phone can store, your telephone company offers call blocking as a service. This works the same way from the caller's perspective — they hear a message or silence — but the blocking happens at the company's equipment, not on your phone.
Call your telephone provider and ask whether they offer call blocking. Most major providers do, though some charge a small monthly fee (usually between two and five dollars) while others include it free with certain plans. Ask them to tell you the cost and what the service is called — common names are Call Block, Call Screening, or Selective Call Rejection.
Once you've activated the service, you can usually manage your blocked list by calling a phone number your provider gives you, or by logging into your account on their website. To block a new number, you either enter it through the phone system, type it into your online account, or call your provider and give them the number. Some providers let you block entire categories of calls — like blocked numbers, private numbers, or numbers outside your area code — without listing each one individually.
Using a third-party call-blocking device
If you want to block calls without relying on your phone or your provider, a call-blocking device plugs into the jack where your phone line enters your home. These devices sit between your wall jack and your phone, screen incoming calls, and block the ones on your blocked list before they reach your phone.
Popular models include the CPF3000 (made by Clarity), the TrueCaller device, and various models sold by Best Buy and Amazon. Most cost between thirty and eighty dollars, though some are more expensive. They work with any landline phone, regardless of age or brand, because they don't need your phone or provider to support them.
To set one up, unplug your phone from the wall jack, plug the device into the jack, then plug your phone into the device. Add numbers to the device's blocked list using its buttons or a companion app on your phone or computer. When a blocked number calls, the device stops the call before it reaches your phone — you won't hear it ring at all.
The main drawback is that you have to buy the device upfront and manage the blocked list yourself. The advantage is that it works when ready, doesn't depend on your provider, and works with phones that are too old to have built-in blocking.
What happens when you block a number
When you block a number on a landline, the person calling that number experiences one of a few outcomes. Most commonly, they hear a message saying the number is not accepting calls or is not in service. Some blocked calls go to silence, or the caller hears a busy signal. The exact message depends on your phone, your provider, or your blocking device.
The caller does not know they've been blocked — they hear the same message they would hear if your line were disconnected or if you had call screening turned on. They cannot tell the difference between being blocked and reaching a number that doesn't accept incoming calls.
On your end, the call does not ring through and does not appear in your recent calls list (though some phones keep a separate log of blocked calls if you want to review them later). You won't know the call came in unless you check that log.
Blocking numbers that hide their caller ID
Some unwanted calls come from numbers that don't display on your caller ID — they show up as "Unknown," "Blocked," "Private," or "No Caller ID." You can't block these by number because you don't know what the number is.
Instead, most providers and phones let you block entire categories. Your telephone company's call-blocking service usually has an option to reject all calls from blocked or private numbers. Your phone's built-in blocking may have a similar option in its menu — look for settings like Block Unknown Calls, Block Private Numbers, or Block Withheld Numbers.
Be aware that blocking all unknown calls means you'll miss calls from legitimate callers who are using a private line — like some hospitals, government offices, or businesses that hide their number for privacy. If you block this category, you may want to check your blocked calls log occasionally to see if you're missing important calls.
When blocking doesn't work or isn't enough
Blocking a number stops that specific number from reaching you, but it doesn't stop other numbers from the same caller. Robocallers and scammers often use different numbers each time they call, so blocking one number may not reduce the calls you receive.
If you're getting many calls from different numbers, a call-blocking device or your provider's service may be more effective than blocking individual numbers, because they can recognize patterns and block whole categories of calls. Some devices and services use databases of known spam numbers and block them automatically without you having to add them yourself.
If blocking isn't stopping the calls, you may also want to register your number on the National Do Not Call Registry (donotcall.gov). This doesn't stop all unwanted calls, but it does reduce calls from legitimate telemarketers. Scammers and robocallers ignore the registry, so blocking remains your best defense against those.
Frequently Asked Questions
Can I block a number if I don't know what it is?
If the number shows on your caller ID, yes — you can block it even if you don't recognize it. If the call shows as Unknown or Blocked, you can block the entire category of unknown calls through your phone's menu or your provider's service, though this means you'll also block legitimate callers who use private lines.
Will the person I block know I blocked them?
No. They hear a message saying the number is not accepting calls or is not in service. They cannot tell whether you blocked them, whether your line is disconnected, or whether you have call screening turned on.
How many numbers can I block on my landline phone?
Most modern landline phones can store between ten and fifty blocked numbers, depending on the model. If you need to block more than that, your telephone company's call-blocking service usually has no limit on how many numbers you can add.
Do I have to pay to block numbers?
Blocking through your phone itself is free. Your provider's call-blocking service may be free or may cost a few dollars per month depending on your plan and provider — call them to ask. Third-party blocking devices cost money upfront but have no monthly fee.
Can I unblock a number after I block it?
Yes. On your phone, go back to the block menu or blocked calls list and remove the number. With your provider's service, call them or log into your account and delete it from your blocked list. With a third-party device, remove it from the device's blocked list using its buttons or app.