A Fax Analog Telephone Adapter (ATA) is a device that allows you to use a traditional fax machine to send faxes using an internet connection. Sometimes called a fax machine adapter, a fax jack, or a fax bridge, a fax ATA makes it easy to modernize your office communications while still using the equipment you’re familiar with — and in some cases, required to use.

In the U.S. and many other countries, governments have given telecom providers the green light to stop maintaining traditional phone lines. In other words, landlines are being phased out in favor of more modern technology, such as fiber optic cable. Once that happens in your area, analog fax machines won’t work without an ATA.

I’ll explain what traditional fax doesn’t work over the internet, how a fax ATA works, the different types available, and how to pick one that works for your needs.

How a fax ATA works

A fax ATA acts as a translator between two different technologies: the Public Switched Telephone Network (PSTN) and the internet. Fax was designed for phone lines, which transmit analog signals. The internet transmits digital data known as packets. The two methods of transmission are not compatible.

Let’s go just a little deeper into both technologies so you can see how a fax ATA provides the missing link and allows any old fax machine to send digital faxes.

A fax machine works the same way as a telephone does — sending analog signals over phone lines — but instead of converting voice to signal, fax converts an image into signals that can be transmitted.

The fax machine scans whatever document you feed into it, translates the document into an image, and then converts it into audio tones that are sent over phone lines. People born before 2000 will remember the beeps and boops that a dial-up modem made — those are the audio tones I am talking about.

Once the audio signal gets to the other side, the receiving fax machine converts those signals back into a visual format and then prints out the original image.

While this works just fine when you’re using a phone line — which is designed to carry analog signals — things are a bit different when you use the internet, which transmits digital data rather than analog signal.

That’s why you can’t send a fax from an analog machine via the internet without a “translator” of some kind; it simply doesn’t know how to create data packets, and so there’s nothing for the internet to send to the other fax machines.

That’s where a fax ATA comes in. It takes the analog signals your fax machine creates from the original visual image and translates them into data packets that can be sent via the internet. Once the data packets reach the other end, they’re then translated back into a visual format capable of being printed.

Installing a fax ATA

While fax ATAs can vary a little bit from model to model, they normally look like small boxes with three sockets in the back. One is for the power cord, and it’s usually labeled as “Power” or sometimes “DC 5V” to denote the kind of power it uses.

Another socket is for the cable that connects the ATA to the fax machine, and it looks like a normal phone jack that you’d use with a landline. This one may be labeled “Fax” or “Phone.” In some cases, there may be more than one of these, which means you can plug the device into several fax machines at once.

There’s another jack that also looks like a traditional landline jack (only bigger), and this one is used to connect to the internet. It might be labeled “Internet,” “Ethernet,” or “WAN/LAN.” If it’s labeled “Internet,” you can plug it directly into your router. If not, you may have to plug it into your computer, assuming your computer has some kind of ethernet port.

This should work the same way, no matter which type of port you have. The only difference is whether the ATA connects to the internet directly or if it connects to the internet via your computer as a middleman.

Since each of these sockets has a different type of cable that should only fit into its respective port, it would take a lot of effort to get things wrong — all you have to do is make sure the right cable is plugged into the right socket, and you’re usually good to go.

How to select the right fax ATA

Some fax ATAs will work better for certain use cases and different business sizes. Some of the best analog telephone adapters will work for landline fax machines, phones, and other legacy communication technology.

If you only need a fax ATA for a home office, you’re likely going to be fine with a simple, one-port ATA that lets you connect to one fax machine. Look for one that’s device-agnostic and uses an open communications protocol, which means that it can work with any type of fax machine and any type of computer.

Most small businesses can get away with using a single port ATA as well — unless they send and receive a lot of faxes and need to be able to operate several fax machines at once.

If this is the case for you, choosing a multi-port fax adapter that lets you connect to several fax machines can be a good idea, and you may want to consider one that connects to phones and fax machines at the same time. If you’re wanting to move your communications to Voice over Internet Protocol (VoIP) but still want to use your analog landline and fax machine, this could be a good choice.

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For large organizations and those who are running a unified communications environment with Session Initiation Protocol (SIP) trunking, an advanced solution may be the smartest choice here.

In this case, you’ll want to look for a system that offers fax ATA capabilities while also allowing you to make internet-based phone calls. This is similar to how a traditional landline Private Branch Exchange (PBX) works, but instead of using the PSTN, it uses the internet.

These devices do everything that a fax ATA does, plus they allow you to connect a bunch of traditional landline phones to the internet for VoIP calls. If you have a modern VoIP phone system, this opens the door to a host of useful call administration features, including call forwarding, call waiting, and advanced security protocols.

Fax ATA codec options

Generally speaking, codecs are software algorithms used to compress, encode, and decode audio signals for transmission over digital networks. For fax transmission, codecs need to handle image data instead of just voice.

This is where the aforementioned “translation” process comes in. The fax ATA is able to convert audio tones generated by your fax machine into digital data that can be sent over the internet.

There are a number of fax codecs, with the most common three being T.30, T.38, and G711, which is also a very popular VoIP codec. Lets go through each codec and when it makes sense to use it.

  • T.30 is designed to be used over an analog telephone line, and it works just fine if you’re sending faxes the traditional way. It won’t work for VoIP faxing unless you have an ATA that can translate the signals in such a way that they’ll be compatible with a T.38 protocol.
  • T.38 is perhaps the most widely used fax codec and is recognized by most machines. In general, it has very low bandwidth, it can handle latency delays of up to a second, and it has fail safes in place to prevent packet loss. However, given the type of signal T.38 creates and how it travels on the PSTN, you can sometimes have issues with the quality of your fax.
  • G.711 is similar to T.38, but it uses much more bandwidth because it converts your signals into audio packets. This works with most machines, but it has much more potential for packet loss than T.38.

The easy alternative to using a fax ATA

One way to get around using a fax ATA is by switching to an online fax service. You might have to purchase a fax ATA if you are dead set on using a fax machine or multifunction printer, but with online fax services, you don’t need those machines at all.

With these services, people can send and receive faxes from their email, phone, tablet, laptop — virtually any device that is connected to the internet will work. The vendor is responsible for maintaining all the infrastructure necessary to send/receive faxes, so as long as you sign into the service, you are all set to fax.

For individuals, there are lightweight apps that will let you send a fax from your iPhone as well as free online fax services you can access via your browser. The free fax options are great if you rarely need to fax. Paid options are much better if you need to store, label, and retrieve faxes later.

For businesses, the major consideration for switching to online fax is compliance. Any reputable online business fax service is going to be secure, but it may not be compliant with privacy and security regulations.

Not every fax service is HIPAA compliant, for example. Some vendors may not offer all the features required, and some that do are still unwilling to sign a Business Associate Agreement, which renders the service non-compliant.

So if your business has compliance responsibilities beyond the norm, it’s definitely a good idea to make sure that any online fax software you select meets all required standards for data encryption, access control, and so on.

Transitioning to online fax isn’t going to be a choice forever. In the U.S., landline infrastructure is on its way out. The Federal Communications Commission (FCC) has said phone providers don’t have to maintain the old PSTN lines — as long as they offer a viable alternative.

The phase out is already happening. An ATA will let you keep using your fax machines and landline devices as normal, regardless of when landlines are phased out in your area.

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