February 9, 2023

Faxing Over IP - All You Need to Know

Like pay phones and DVD players, fax machines may be ancient technology, but they’re not obsolete. 

In fact, around 43 million fax machines are still in operation in the US alone. Thanks mainly to the medical and legal fields and other regulated industries that keep these machines alive.

Indeed, fax technology has significantly progressed; you can now send faxes using your computer or smartphone. You can even send faxes with no fax machine at all. And we call this new technology Fax over IP (FoIP). It skips the telephone line when sending messages. 

But is it really worth considering for your business?

In this guide, we’ll help you to quickly understand what Fax over IP means, how FoIP works, if it is reliable and its benefits over the traditional fax machine. Ready? Let’s begin.

What is Fax Over Internet Protocol (FoIP)?

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Fax over Internet Protocol is a technology that allows you to send or receive faxes over an IP network (local or wide area) instead of the traditional PSTN (traditional circuit-switched telephone) network. 

Thus, the new method reduces the need for a clunky fax machine in your office and cuts the cost per document sent. 

FoIP works almost the same as the VoIP network but with an added network bandwidth. The additional bandwidth allows you to send more fax documents and ensures your fax data is accurate.

Ultimately, FoIP is the better option because it increases the security of your fax process and allows your team to work more efficiently.

With Thatch, you can send faxes directly from your computer. Try it for free and see how it works!

What Are the Benefits of Fax Over IP (eFaxing)?

  • Using Fax Over IP is easy as it doesn’t need a separate analog network but instead taps into your existing network.
  • FoIP creates an image file for the fax. So, files are quickly sorted, archived, and emailed to other recipients.
  • It allows remote workers to receive faxes even if they don’t have fax machines.
  • FoIP can save you money. You don’t have to pay for traditional phone lines or install new hardware. The expense is already included in your internet package.
  • It offers a more straightforward means of transmitting sensitive documents.
  • It’s more efficient to send and receive documents in high volume.
  • You can fax from any location without a need for a fax machine.
  • FoIP is compatible with multiple platforms. It doesn’t need any specific operating system or device.

Why would you fax if you can email?

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While many people use email to send and receive their documents, there are matters concerning data security, privacy, efficiency, and speed with such a method of exchanging messages. These are why others would still prefer to fax important documents than email. 

Fax machines are more secure than web-based email services

Fax machines are more secure than email because they use a network that’s less susceptible to cyber threats. 

For traditional faxing, it uses a telephone network, and for FoIP, they’re using military-grade encryption. This standard is also called AES-256 encryption, established in compliance with the law governing sensitive data handling.

That level of encryption is difficult to intercept. And even if the data is intercepted, it would still take billions of years for brute force to crack it. So, it's the best encryption if you want to show your customers that you care about their personal data.

Once the fax server or a faxing software program is installed into your company’s system, it can accept documents, convert them into fax formats, and transmit data using any interface.

Unlimited cloud storage with FoIP

In terms of storage, faxing over IP has more advantages over email. Most email providers don’t offer unlimited storage. If they do, they’ll ask you to pay extra for it.

With FoIP, you have a better storage option without paying an additional fee aside from the subscription. This feature is handy, especially if you have to fax in high volume.

The good news is that if your organization already uses fax servers for email integration, web access, and desktop messaging, it’ll be easier to migrate most of your environment to FoIP. But how reliable is FoIP?

Is It Safe to Fax Over IP?

Yes, sending faxes over IP is safe because it’s an encrypted process. There’s an added layer of security to your document control activities and your faxing to make them less accessible to potential hackers.

Some online fax providers, like Thatch, even specialize in solutions for specific use cases and highly regulated industries.

How Does Fax Over IP Network Function?

Source: Pexels

FoIP works by digitizing the document, making it into data packets, and sending them via your computer or phone. The other user receives the data packets, reassembles the original document, and finally sends it to the fax machine. This entire process doesn’t use a telephone line.

That said,  you can fax online wherever you are, without ever paying for expensive per-charges or searching nearby fax services. You can combine the custom features into your existing fax software or online fax system to schedule and automate faxes.

Anyone in your team may also access the fax software with their computer or smartphone and send faxes without printing papers.

Most of all, the user experience is almost the same as traditional faxing. It has the same feel and responsiveness. Users on both ends (sender and receiver) can send and receive the fax message in real-time.

The challenge of FoIP: lost or out-of-sequence packets

Still, no technology comes without challenges. For FoIP,  lost packets of data caused by network congestion can lead to a fax call failure. Since there’s no sequence to read, the fax isn’t transmitted.

This can be mitigated by various error correction techniques, such as increasing bandwidth, adjusting the quality of service on the router, or through redundant packets - requiring two consecutive packets to be lost for any data to be lost.

Common reasons organizations switch to FoIP:

  • They want to consolidate fax/voice and data.
  • They want to switch from analog to an all-IP environment (meaning, no copper lines).
  • They must eliminate or lessen hardware, maintenance, and other equipment costs.
  • They opt to migrate their business operations to virtualized environments
  • They are moving towards an entirely IP facility.

If any of these appeals to your organization, FoIP technology may be the best choice for your business too!

Different Types of FoIP Technology and Why They Matter

Now that we’ve discussed fax protocols, let’s get more technical and learn what they actually are. Remember that choosing which protocol to use is your most important decision related to FoIP.

Source: Pexels

T.30 (industry-standard for analog fax type)

The first type of FoIP is the T.30. The T.30 protocol is the fax handshake protocol that creates and maintains communication between two fax devices. It’s the industry standard for analog fax type, which uses a public switched telephone network (PSTN).

Before the advent of the internet, T.30 and fax were so entwined they were synonymous. In fact, T.30 was the ITU recommendation for transmitting faxes through the public switched telephone network.

T.30 includes a mechanism to handle spikes of interference and background noise on the telephone line. For instance, the poor signal quality can be addressed by reducing the transmission speed, and noise spikes can be accommodated by retrying any operations lost during the spike.

T.30 can be used to send a fax over IP but may not be your best choice.

Choosing between T.30 and T.38 comes down to experimentation. Which of the two works best may depend on the quality of the IP link of your telephony service provider.

T.37 (stores and forwards faxes using the internet)

A fax machine configured to T.37 uses SMTP or MIME to translate faxes into emails and vice versa. In short, it stores and forwards fax messages using the Internet. 

FoIP technology sends fax as a MIME-encoded email attachment using Simple Mail Transfer Protocol. T.37 implementations with a gateway allow companies to receive faxes as email even if they’re sent using a traditional fax machine on the PSTN. Similarly, companies can send emails over the PSTN as faxes.

T.38 (send fax in real-time)

The T.38 protocol reliably dictates how fax audio crosses a packet-switched network, like a company’s LAN/WAN or Internet. For that to happen, the analog signal used by fax machines is converted into digital packets. The real challenge here, though, is reliable fax over IP.

Voice over IP networks or services is usually optimized for voice calls. Compression is applied to lessen the bandwidth needed to carry the call. Users tolerate poor connections where latency or packet loss may cause a “choppy call” experience - gaps in the voice stream.

Fax, however, is not nearly as forgiving. The network must have minimal jitter, latency, and other elements that lead to packet loss. Enabling T.38 can correct packet loss and reduce the required data network bandwidth. 

Hence, T.38 creates to provide a reliable real-time FoIP. This is also why T.38 is the preferred approach to faxing and is built in many IP routers.

Why T.38 fax protocol is the recommended choice

T.38 fax protocol is often the recommended choice for fax over IP because it sends in real-time and is more confidential.

G.711 (backup in case a T.38 call doesn’t go through)

The G.711 protocol turns analog signals into digital ones. It requires a high bandwidth because it utilizes an uncompressed format and works like a VoIP call, wherein every part of the fax is sent via voice packets. 

This protocol simplifies the fax solution and makes it more cost-effective as well. However, it can lead to sending failure or degradation of fax quality if some voice packets are lost during transfer.

Why Businesses Choose Thatch for Their Faxing Needs

Thatch’s FoIP solution helps you manage your business faxing needs via your network infrastructure.


Although Thatch is less expensive than other online fax services, we don’t compromise on quality. And as discussed above, FoIP allows you to fax without relying on phone lines. This means you don’t have to spend extra for phone line installation or buy fax machines and their accessories for your faxing needs.

Efficient and speedy 

The transfer is more efficient and faster when you fax through the internet. Your business is also less likely to experience interruptions or delays.


Thatch has advanced privacy and security features, like an option on how you want the service to store your received and sent faxes. It also eliminates the need for a Publicly Switched Telephone Network when sending a fax message.

Don’t worry about data threats because Thatch has one of the most secured measures in FoIP available on the market today. It uses military-grade encryption, so your documents are safe with us.

FoIP allows you to do that even if you need to fax to an international number. The process is exactly the same as you send locally.

Ease of use

Feel the convenience of sending and receiving a fax from your smartphone, laptop, desktop, or tablet. You can fax virtually anywhere as long as you have stable internet.

Environmentally friendly

Do you prefer to keep your old fax machine? No problem! Our FoIP solution can connect your fax machine to the Internet through an analog terminal adapter. This eliminates your long-distance charges and cuts the line cost.

But why not go paperless and send and receive faxes from your computer? 

Going paperless with Thatch means no more fax machines to maintain, no more toner and paper to buy, and no more fax line costs. 

Our clients who went paperless even never looked back. They saw their costs go down heavily and loved getting their fax messages delivered to their inboxes. You can enjoy these same benefits too!

Key Takeaway

When implemented well, faxing over IP is a game-changer for any business. It can do the same to your business too! It’ll ensure that you can fax anywhere at any time.

All you need is an internet connection and you can already send invoices, signed contracts, medical records, agreements, and more to your recipients. You can also receive as many faxes as you want without relying on business phone lines. Finally, unlike traditional faxing, you won’t ever have concern over packet loss or baud rates.

We hope this guide on faxing over IP has helped you decide why it’s worth the switch to FoIP.

Are you looking for the best online fax service that supports multi-platform faxing? Thatch allows you to fax conveniently using your computer, smartphone, or tablet! Request for a 14-day free trial account today.

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