What Is a Fax ATA and How To Select the Right One


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

How a Fax ATA Works

A fax machine works the same way as a telephone does, only instead of sending audio signals, it sends pictures. The way this works is that the fax machine scans whatever document you feed into it, translates the document into an image, and then sends it down a phone line as an audio signal. Once the 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. This is because the internet doesn’t carry analog signals. Instead, it carries packets of data. 

Another way of looking at this is to think of it as speaking a different language; while the basic process is the same (because a signal is created on one end, sent to another, and then reconstituted in its original form), each medium is built for a different type of signal (or language). 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 an 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.

While 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. 

Finally, 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. 

Keep in mind that 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 ATAs may work better for certain use cases and different business sizes. 

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). 

If you have simple needs, you won’t need to worry about any of the extra software or fancy bells and whistles, but you may still want to shop around for a model that comes with robust support. Most single-port ATAs are easy to set up, but it never hurts to have a good customer support network in your back pocket.

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 over to a VoIP provider but still want to use your analog landline and fax machine, this could be a good choice.

Finally, 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 Public Switched Telephone Network (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 VoIP service, this opens the door to a host of other features, including call forwarding, call waiting, and advanced security protocols.

Fax ATA Codec Options

A codec is a piece of software or hardware that compresses or unpacks data. This is where the aforementioned “translation” process comes in to convert visual signals captured by your fax machine into analog signals or data packets (depending on what kind of technology you’re using to send the fax). 

There are a number of fax codecs, with the most common three being T.30, T.38, and G711.

  • 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, however, 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 failsafes 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.
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