How to Block Unwanted Faxes

By D. Laverne O'Neal

Updated September 26, 2017

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A fax machine is a great convenience, as it allows you to receive facsimiles of documents, including signature copies, in your home or office via a telephone line. Of course, every communications convenience carries the potential for abuse. Just as you may receive phone calls you do not want, you may also find yourself receiving unwanted, unsolicited faxes from concerns unknown to you. You can block them using a call-blocking service or a number-blocking feature that exists on your fax device. You can also try contacting the concern directly.

Contact the Sender

Get the fax number, or wWeb or email address of the sender. You may be able to find the information somewhere on the fax. Check the bottom of the fax to find the number from which it was sent, for example. If you cannot find any address or number to reply to, and a company name is provided on the fax, you can try searching the web for the company's contact information.

Compose a request to opt out of the sender's list of contacts. Write or type a note asking that your fax number be removed from the faxer's contact list. Be sure to include your fax number in the note. Though it seems redundant, take care to ask also that the sender no longer send you faxes. You might also include information regarding the illegality of the company's failing to abide by your request, as no "business relationship" exists between you and the sender company.

Send the opt-out letter to the contact number or address of the unwanted faxer. If, after sending the letter, you continue to receive faxes from that sender, you can file a complaint with the FCC, and inform the company that you have done so.

Use Fax Number-Blocking Feature

Check to be sure your fax line is equipped with Caller ID. If you do not recall this service detail, contact your telephone service provider to confirm.

Find the instructions for blocking fax numbers. In a printed manual, you can consult the table of contents or index. In an online manual, you may want to type into the request field keywords, such as 'fax number blocking'.

Activate your fax blocking feature by following the manual instructions. Depending on your available options, you may be able to search the numbers of faxes you have received, or even enter by hand a number you want to block.

Use a Fax-Blocking Product

Search the Web for fax blocking products. You can use any search engine to find a product to suit your needs. Certain sites list a range of fax blocker products. You can also find product reviews online.

Purchase the product. You can usually buy online or by phone.

Follow instructions to setup and use the product. Your device may, for example, allow you to specify numbers or prefixes to block, specify numbers to allow, and/or simply block all unidentified numbers, among other options.

Use 'Call Block' Services

Contact your telephone service provider. You can usually reach them by phone, email, and/or chat.

Find out what kinds of number blocking services are offered. Your phone service provider may allow you to refuse calls from unidentified numbers, or specify numbers to block, for example.

Choose the best service for your needs. If you primarily want to avoid faxes from unidentified numbers, select only that call blocking choice. If you want to stop certain numbers from ringing on your phone, choose that option. Call blocking services typically require a monthly or annual fee in addition to any existing monthly phone fees.


If you send an opt-out communication but continue to receive unwanted faxes from the sender, you can sue the sender. For more information about pursuing junk faxers, you can contact the FCC, your state Attorney General, or your state consumer protection agency.


Contacting junk faxers by phone may backfire, as it may allow the offending company to capture your phone number. This may result in annoying phone calls, in addition to the faxes.