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What Is a Fax Number?

what is a fax number

Faxing has long been one of the preferred file-sharing methods due to the safe process of transmitting information over phone lines. With innovations like online faxing, file safety has only increased, thanks to protective measures like encryption.

But how exactly does a fax relate to phone numbers, and what is a fax number? And do you still need a fax number to fax online? We have the answers to those questions and more. Let’s dig in.

Fax Number Meaning

So, what is a fax number? 

A fax number is just a telephone number used for transmitting documents. It refers to the number you dial on the fax machine when sending a fax — or the number people use to send you a fax. 

Fax numbers can be either analog telephone lines or online phone numbers — just like phone numbers can correspond to a physical landline phone or a cell phone.

What Is a Fax Number Used for?

A fax number is used for sending and receiving documents. It offers an alternative to snail mail, email and other file-sharing methods. 

But why choose a fax number over something like email? Here are a few use cases:

  • Sending and Receiving Documents: Faxing — especially online faxing — facilitates file-sharing. Not only can you quickly share digital documents, but with eFax’s mobile app, you can scan physical documents and fax them in mere minutes right from your phone.


  • Increased Security: Since its conception, faxing has been an easy way to share documents without compromising security. Physical documents can get lost in the mail and email can be hacked. Standard faxing, though, sends information through telephone lines, which are much more protected. And online faxing offers even more protection with high-level encryption.


  • More Privacy: When physical faxes arrive at the receiving machine, they can easily be forgotten or fall into the wrong hands. This can result in confidentiality breaches and noncompliance. Online faxing with eFax uses safety measures like encryption and multi-factor authentication so that the data remains private.


  • Greater Accessibility: With online faxing services like eFax, you can send and receive faxes from anywhere. Just open the eFax mobile app or the Messenger desktop app and review your documents. This can drastically reduce turnaround times and cut costs. 

How Does a Fax Number Work?

Traditionally, fax numbers allow two fax machines to communicate and transmit information through audible tones.

A fax machine is plugged into a physical telephone line. When you dial a fax number to send a document, the fax machine ‘calls’ the other fax machine and uses a shared language of audile tones to ‘read’ the document. The receiving machine then prints out the transmitted language.

Online faxing is now becoming more popular, removing the dependence on physical machines. It uses a dedicated phone number to virtually transmit documents, with no physical connections needed.

Fax Number Format

Fax numbers have the same format as regular telephone numbers. In the United States, that means your fax number would have the same 10-digit format that standard phone numbers have. The first three digits would still be the area code, while the last seven digits would be the actual number. 

International Fax Numbers

For international faxes, the number might not have the 10-digit format. It depends on how phone numbers are structured in that country. For example, U.K. numbers include 11 digits, not 10.

You would also need to add the country code to the international fax number, just like you would for phone calls. The country code is the + symbol, followed by the geographical code assigned to your country. To send a fax to a U.S. fax number (from outside the country), just add a +1. Likewise, you must add +44 to fax to the U.K., +99 to fax to India and +52 to fax to Mexico. 

If you don’t know the country code for the recipient’s location, you can look it up with a quick online search.

Toll-Free vs. Local Fax Numbers

Fax numbers aren’t random phone numbers. You can get dedicated fax numbers with a specific area code corresponding to your business’s location. 

Businesses with a local clientele might prefer a fax number with a local area code to boost trust with their clients. Or, companies with multiple locations might select a local fax number for each branch. 

Larger companies might prefer a toll-free fax number for their diverse customer base. Toll-free numbers typically help build trust with clients, showing them that they are a well-established business.

Fax Numbers vs. Phone Numbers

Since fax numbers and phone numbers have the same format, does that mean they’re the same thing? 

  • Yes and no. 

A fax number is, technically, a regular phone number. To work, fax machines must be connected to a physical telephone line. If you plug a phone into that landline instead of a fax machine, it would work for calls. 

Some companies have even used the same number for faxes and calls, although that is no longer common practice. You could technically call a fax number and talk to a person or send a fax to that same number. The downside, of course, is that businesses couldn’t call and receive a fax at the same time. And if they picked up the phone on an incoming fax, it would stop the transmission. 

How to Tell If a Number Is a Fax Number

There’s no way to differentiate between a telephone and a fax number just by looking at them. They have the exact same format, with an area code and country code (for international communication). 

Companies usually label their telephone numbers so you don’t have to guess. You might find something like this on their website or business card:

  • Tel: 855-555-5543
  • Fax: 855-555-5544

If you can’t find that information, you can try calling the number. You likely won’t get through to a person if it’s a fax number because businesses typically keep their fax and calling lines separate now. However, if you call a fax number connected to a physical fax machine, a machine will answer with a series of beeps.

What Is a Fax Number for Online Faxing?

An online fax number is the same as an analog one but without the physical telephone line. You don’t need to plug our fax machine into the landline — in fact, you don’t even need a fax machine at all. 

Instead, virtual fax numbers let you send and receive faxes anywhere and anytime. By getting an online fax number through a company like eFax, your phone, tablet, computer or laptop can become a fax machine. And the best part is that your recipient doesn’t need to have a virtual fax number. 

You can send a fax to any other fax number, even if it’s connected to a fax machine. Customers, clients and colleagues can also use a physical fax machine to send documents to your virtual fax number. You won’t physically receive the file like with a fax machine, but it will arrive in your inbox within minutes — if not seconds.

Online Fax Number Format

Virtual fax number formats are the exact same as a traditional fax number — and, therefore, a standard phone number. With online faxing companies like eFax, you can request any type of fax number: international, toll-free or local. 

How to Get a Fax Number

Anyone can get a fax number — and it only takes a couple of minutes with online faxing provider eFax. But before exploring that option, here’s how to get a traditional fax number.

Traditional Fax Number

Traditional faxing depends on a physical telephone line connected to your fax machine. Unfortunately, landlines are now becoming less common, both for individuals at home and large businesses. It’s no longer the norm to have phone jacks in every room. 

That may mean you need to get a landline and phone jack installed in your home or office to start faxing. When you contact your phone company to get the landline installed, you can discuss your options for a fax number. 

Now, if you already have a landline phone installed, you can switch that to fax by plugging the fax machine into the phone jack. If, for some reason, you don’t know what the number is for that line, you can call your cell phone from that line before connecting your fax machine. The number will appear on your phone screen. Once you plug the fax machine into that phone line, that number will be your new fax number.

Virtual Fax Number

Getting a traditional fax number can be a bit of a hassle if you don’t yet have a traditional landline. Thankfully, there’s a simpler option: online fax numbers. 

With providers like eFax, you can find a fax number in less than five minutes. Just go to eFax’s website and start a trial. The first thing you’ll see is a suggested fax number based on your location, plus the option to select a custom fax number (toll-free, local or international). Pick the one you want, fill in your personal information and that’s it. You have a virtual fax number.

Frequently Asked Fax Number Questions

A fax number refers to the number used to transfer documents via a phone line. Fax numbers were traditionally a physical landline, but they now include online fax numbers.

Getting a fax number is easy with eFax. Just sign up for a trial and choose the suggested fax number. You can also port an existing fax number or select a specific international, local or toll-free number. 

Yes, a fax number is essentially the same as a phone number. You can either use the number for faxing or for calling. With physical fax machines, you can technically use a fax number as both a faxing and calling line, although it’s extremely inconvenient. Online fax numbers are only for faxing and have no correlation to a physical phone.

Here are a few examples of fax numbers: 

  • Toll-free fax number: 1-888-555-1234
  • International UK fax number: +44 121 1234 5678
  • Local fax number for Houston, TX: 281-555-4321

You need a fax number for any type of faxing, whether international or local. The good news is that you don’t need a fax machine. With a fax number from eFax, you can send and receive faxes right from your phone or computer.

If you have a physical landline, you can use that as a fax number by connecting a fax machine to the phone jack. However, you cannot use a cell phone number as a fax number. eFax makes it easy to get a separate fax number when you sign up for a trial — it takes less than five minutes.

Why Choose eFax for Your Faxing Needs

Quickly getting a fax number is just one of the many benefits that eFax offers. Another is the increased flexibility in document-sharing workflows.

Once you’ve created your account, you can start faxing right from your email, the eFax mobile app, the Messenger desktop app and even a Word doc. Make sure to give people your virtual fax number so they can send you faxes as well. You’ll get a notification in your email and eFax account as soon as the fax arrives, allowing you to handle correspondences immediately from anywhere.

Ready to see for yourself how easy it is to get a virtual fax number? Start with eFax today.

Send and receive faxes in minutes.