Blocking a number on a landline depends on what your phone company offers

Most landline providers now offer call-blocking tools, but the method varies by company and your phone model. Some services are built into your phone line itself — managed through your provider's website or a phone call to customer service. Others require a separate device that sits between your wall jack and your phone. A few older landlines have no blocking option at all, which means you would need to switch providers or add a third-party device to screen calls.

The fastest way to find out what you have access to is to call your landline provider directly and ask what call-blocking options come with your service. They can tell you whether it is included free, costs extra, or requires equipment. If your provider offers nothing, a call-screening device like a call blocker box — a small device that plugs into your phone line — can block numbers without changing your service.

Key Takeaways

  • Most landline companies offer call blocking through your account, either free or for a small monthly fee, and you manage it online or by phone.
  • Your phone model matters: newer phones may have a built-in block list, while older rotary or basic phones cannot block calls on their own.
  • If your provider does not offer blocking, a standalone call-blocker device plugs into your phone line and filters calls before they ring your phone.
  • Blocking a number usually takes one phone call to your provider or a few clicks on their website, and takes effect within hours.

How to block a number through your landline provider

Call your landline company's customer service number — usually printed on your bill — and ask for their call-blocking service. Have the phone number you want to block ready. The representative will add it to your account, and the block usually takes effect within a few hours. Some providers let you block up to 30 numbers; others have no limit.

If your provider has an online account portal, you can often add blocked numbers yourself without calling. Log into your account on their website, look for a section called "Call Management," "Call Blocking," or "Do Not Disturb," and enter the number. The exact name and location of this menu varies by company — Verizon, AT&T, and CenturyLink all organize it differently — so check your provider's help page if you cannot find it.

Some providers charge a small monthly fee for call blocking, usually $3 to $5. Others include it free with your service. Ask during your call whether it costs anything before you set it up.

Using your phone's built-in block list

If you have a newer cordless or digital landline phone, it may have its own block list separate from your provider's service. Check your phone's manual or the manufacturer's website to see if your model supports blocking. On most modern phones, you press a button or menu option while a call is ringing, select "Block This Number," and the phone remembers it.

The advantage of phone-level blocking is that it works when ready and does not depend on your provider. The disadvantage is that the number is blocked only on that one phone — if you have multiple handsets in your house, you would need to block the number on each one separately. Also, if your phone loses power or you replace it, the blocked numbers may be erased.

Older rotary phones and very basic landline phones do not have this feature. If your phone is more than 15 years old and has no digital display, it almost certainly cannot block numbers on its own.

Adding a call-blocker device to your line

If your provider does not offer call blocking or you want more control, a call-blocker box is a small device that plugs into the wall jack where your phone line enters your house. Your phone plugs into the device instead of directly into the wall. The blocker screens incoming calls against a list you create and either silently drops blocked calls or sends them to a voicemail the caller cannot reach.

Popular models include the CPF3000 and the Nomorobo device. These typically cost $40 to $100 upfront, with no monthly fee. You add numbers to block through a small keypad on the device or through a companion app on your phone. Some devices also block calls from numbers that do not show a caller ID, which catches many spam calls automatically.

The setup takes about five minutes: unplug your phone from the wall, plug the device into the wall jack, and plug your phone into the device. No installation or technical knowledge is required. If you have multiple phones in your house, you can plug them all into the same blocker, and all of them will respect the same block list.

What happens when a blocked number tries to call

When someone calls from a number you have blocked, the call does not ring your phone. Depending on your setup, the caller either hears a message saying the number is not in service, gets sent to voicemail, or straightforward hears silence and the call drops. Most systems do not notify you that a blocked call came in — it straightforward disappears.

If you want to know which blocked numbers tried to reach you, some call-blocker devices keep a log you can review. Your landline provider's blocking service usually does not provide this information, though you can ask when you set it up.

Blocking calls from numbers that hide their identity

Many spam and scam calls come from numbers that do not display on your caller ID — they show up as "Unknown," "Private," or "Blocked." You cannot block a specific number if you do not know what it is. However, you can block all calls from hidden numbers.

If your provider offers this option, ask them to enable "Block Anonymous Calls" or "Block Restricted Calls" on your account. This stops any call that does not transmit a caller ID from reaching your phone. The downside is that some legitimate callers — hospitals, government offices, and businesses with older phone systems — sometimes call from hidden numbers, so you may miss important calls.

A call-blocker device gives you more flexibility: you can set it to silently drop calls from hidden numbers, send them to voicemail, or let them through. This way you control the behavior rather than accepting an all-or-nothing rule from your provider.

When blocking does not work and what to do instead

If you block a number and calls keep coming from it, the caller may be spoofing — using technology to make their call appear to come from a different number each time. Spoofed calls cannot be blocked by number because the number changes with each call. In this case, blocking individual numbers is not effective.

If you are receiving repeated unwanted calls, report them to the Federal Trade Commission at ReportFraud.ftc.gov. If the calls are threatening or harassing, contact your local police department. Your landline provider may also be able to help identify patterns in the calls and suggest additional blocking options.

If your provider's blocking service is not working — you block a number but it still rings through — call customer service and ask them to verify the block was applied correctly. Sometimes blocks fail to set up due to a system error and need to be re-entered.

Frequently Asked Questions

Can I block a number if I do not know who it is?

Yes. You can block any number that appears on your caller ID, whether you know who it is or not. If the call shows a number, you can block it. If it shows "Unknown" or "Private," you cannot block that specific call, but you can ask your provider to block all calls from hidden numbers.

Will the person I block know that I blocked them?

No. When a blocked number calls, they hear a message that the number is not in service or the call straightforward drops. They do not receive a notification that you blocked them. From their perspective, your line appears to be disconnected or unavailable.

Can I unblock a number after I block it?

Yes. If you block a number through your provider, call them back and ask them to remove it from your block list. If you blocked it on your phone or through a call-blocker device, access the same menu where you added it and delete it. The unblock usually takes effect within hours.

Do I need to pay extra to block numbers?

It depends on your provider. Some include call blocking free with your service. Others charge $3 to $5 per month. A standalone call-blocker device costs $40 to $100 upfront with no monthly fee. Ask your provider what they charge before you set it up.

What if my landline provider does not offer call blocking?

Older or smaller landline providers sometimes do not have this service. In that case, a call-blocker device is your best option. Plug it into your phone line, add numbers to block, and it works independently of your provider. You can also switch providers if blocking is important to you.