Blocking a number on a landline depends on what your phone company offers
Most landline providers offer call blocking through their network, meaning the phone company stops the call before it reaches your house — you do not have to buy extra equipment or change your phone. The exact name and cost varies by provider. Verizon calls it Call Filter; AT&T calls it Call Protect; smaller regional carriers may call it Anonymous Call Rejection or Call Block. Some providers include basic blocking free; others charge $3 to $5 per month. A few still offer nothing at all.
If your provider does not offer network-level blocking, or if you want to block calls without paying a monthly fee, you can buy a standalone device that sits between your wall jack and your phone. These devices let you build a block list and reject calls before they ring through. The trade-off is that you have to buy the device upfront — usually $30 to $100 — and manage the list yourself.
Key Takeaways
- Call blocking through your phone company works at the network level and stops calls before they reach your phone, but the service name and cost depend on which provider you use.
- You can block specific numbers by calling your provider's customer service or logging into your online account, and the process takes a few minutes.
- Standalone call-blocking devices plug into your phone jack and let you build your own block list without paying a monthly fee, though you have to buy the device first.
- Some devices also block calls from numbers that hide their caller ID, which network-level blocking usually cannot do.
- If you receive calls from a spoofed number (one that looks local but is not real), blocking that specific number will not stop the calls, because the caller uses a different number each time.
How to block a number through your phone company
Call your landline provider's customer service number — it is on your bill — and tell them you want to block a specific number. They will ask for the number you want to block and may ask why (harassment, spam, wrong number). Write down the confirmation number they give you. The block usually takes effect within 24 hours, though some providers set up it when ready.
If you prefer not to call, most providers let you manage blocks through their website or mobile app. Log in to your account, look for a section called Call Management, Call Filter, or Call Protect, and add the number to your block list. Verizon and AT&T both let you do this online without calling. Smaller carriers vary — check your provider's website to see what options they offer.
There is no limit to how many numbers you can block, but blocking works only for the exact number you enter. If a caller uses a different number each time, you will have to block each one separately. This is why blocking is effective for a specific person or business calling repeatedly, but not for spam operations that rotate through thousands of numbers.
Standalone devices that block calls without a monthly fee
A call-blocking device sits between your wall jack and your phone. When a call comes in, the device checks the number against your block list and either stops the call or lets it ring through. Popular models include the CPF3000 (around $50), the Nomorobo device (around $60), and the Sentry (around $40). All three work with any landline and any phone — you do not need to change your service or buy a new phone.
To use one, you plug it into the wall jack where your phone cord normally goes, then plug your phone into the device. You build your block list by pressing buttons on the device or by logging into a companion app on your computer or phone. Some devices let you block entire area codes or prefixes, which is useful if you are getting repeated calls from a particular region.
The main advantage is that you own the device and do not pay a monthly fee. The main disadvantage is that you have to manage the block list yourself — when you get a spam call, you have to add that number to the device rather than just calling your phone company. Some devices also require a one-time setup fee to set up their spam database, though this is usually under $20.
Blocking calls from hidden or private numbers
If you are getting calls from numbers that show up as "Private," "Blocked," or "Unknown," network-level blocking usually cannot help, because there is no specific number to block. Your phone company can turn on Anonymous Call Rejection, which rejects all calls that hide their caller ID, but this also rejects legitimate calls from hospitals, government offices, and some businesses that use private numbers for security reasons.
Standalone devices handle this differently. Some let you reject all private calls outright. Others let you set it so private calls ring once and then are rejected, giving you a chance to answer if you recognize the caller's voice. A few devices require private callers to enter a PIN before the call goes through. Check the device's manual to see which option it offers.
If you want to block private calls but still receive calls from specific organizations (your doctor's office, your bank), ask those organizations whether they can call from a regular number instead. Many will do this if you request it.
What to do if the caller uses a spoofed number
A spoofed number is one that looks real but is not — for example, a call that shows your own phone number, or a number that looks local but is actually from a spam operation across the country. Blocking the number you see on your caller ID will not stop the calls, because the next call will come from a different spoofed number.
For spoofed calls, your best option is to report them to the Federal Trade Commission at reportfraud.ftc.gov. This does not stop the calls when ready, but it helps law enforcement track patterns. You can also report spoofed calls to your phone company — they track these reports and sometimes take action against the source.
Some standalone devices include a spam database that learns to recognize spoofed calls based on patterns (calls from numbers that do not exist, calls from numbers that claim to be from your own area code but are not). These devices may catch some spoofed calls even if you have not blocked them specifically. Check the device's description to see whether it includes this feature.
Blocking calls from telemarketers and robocalls
Telemarketing calls and robocalls are different from calls from a specific person or business. Telemarketers are required by law to honor the National Do Not Call Registry, which you can join for free at donotcall.gov. Register your landline number, and telemarketers should stop calling within 31 days. This does not stop calls from charities, political organizations, or companies you have done business with in the past 18 months.
Robocalls — automated calls that play a recorded message — are harder to stop because many come from spoofed numbers. Your phone company's call-blocking service may include a robocall filter that learns to recognize common robocall patterns. Standalone devices sometimes include this too. Neither method catches all robocalls, but both reduce the volume.
If you are getting repeated robocalls from the same number, blocking that number will work until the caller switches to a new number, which usually happens within days or weeks. The National Do Not Call Registry does not cover robocalls, so reporting them to the FTC is more useful than registering with the registry.
Comparing phone company blocking versus standalone devices
The choice between network-level blocking and a standalone device depends on your budget, how many numbers you need to block, and whether you want to manage the list yourself. If you make one phone call and rarely need to add new blocks, phone company blocking is simpler. If you get frequent spam calls and want to avoid monthly fees, a standalone device pays for itself within a year.
Some people use both: they pay for their phone company's robocall filter to catch automated calls, and they use a standalone device to block specific numbers they know about. This gives you two layers of protection without much extra work. Check what your phone company offers first, then decide whether a device would help with the calls that still get through.
| Feature | Phone Company Blocking | Standalone Device |
|---|---|---|
| Upfront cost | Usually free or $3–$5 per month | $30–$100 one-time purchase |
| Setup time | 5 minutes (one phone call) | 15–30 minutes (unbox, plug in, add numbers) |
| Blocks specific numbers | Yes | Yes |
| Blocks private/hidden calls | Only if you turn on Anonymous Call Rejection (may block legitimate calls) | Yes, with options to allow specific callers |
| Blocks robocalls | Some providers include a robocall filter | Some devices include a spam database |
| Works with any phone | Yes | Yes |
| Requires you to manage the block list | No (phone company does it) | Yes |
Frequently Asked Questions
Can I block a number if I do not know my phone company's name?
Your phone company's name is on your phone bill, usually at the top. If you cannot find your bill, call the main number on your phone and ask to speak to customer service — they will tell you which company provides your service. Once you know the name, search online for "[Company name] call blocking" to find the right service and phone number.
What happens if I block a number and then want to unblock it?
Call your phone company and ask them to remove the number from your block list, or log into your account online and delete it yourself. For a standalone device, press the button or use the app to remove the number from your block list. Both take a few minutes. The unblock takes effect when ready or within a few hours.
If I block a number, will the caller know I blocked them?
No. When you block a call through your phone company, the call does not reach your phone at all — the caller hears a message saying the call cannot be completed. When you block a call with a standalone device, the same thing happens. The caller does not receive a notification that you blocked them specifically.
Can I block all calls from a certain area code?
Some phone companies let you block entire area codes through their call-blocking service — ask your provider whether this option is available. Most standalone devices also let you block by area code or prefix. Keep in mind that blocking an entire area code will reject all calls from that region, including calls from people you know.
Do I need to block a number if I just do not answer the call?
Not answering stops that one call, but the caller will usually try again. Blocking prevents the call from ringing at all, so you do not have to see the number on your caller ID or hear your phone ring. If you are getting repeated calls from the same number, blocking is more effective than ignoring the calls.