Examining The Differences Between T.38 And Cloud-Based Fax

December 2, 2020

As you probably know, fax is a mission-critical document transfer solution for many companies and organizations. This is true despite the competition fax receives from emerging communication tools. T.38 fax and cloud-based fax are two of the options available when choosing a modern fax solution. Knowing how these solutions differ, and what each one offers, empowers you to find the best fit for your organization based on your specific needs.

Here are a few of the characteristics of these two types of fax:


  • T.38 is a standards-based protocol that defines how a real-time fax call is carried over the Internet (FoIP) without having to convert it into a voice call (VoIP)
  • T.38 eliminates the high cost tied to using legacy “copper based” telephone services to transmit faxes
  • T.38 is real-time fax: Unlike Cloud-Based Fax and HTTPS-Based Fax solutions, T.38 does not use a “middleman” fax server in the cloud to store data before sending


  • Cloud-based fax solutions address the need to send and receive electronic documents 
  • Cloud-based solutions transfer email to fax and fax to email
  • Cloud-based faxing is a store-and-forward fax, meaning that there is an intermediary between the sender and receiver

Of these features, arguably the most important differentiator between cloud-based and T.38 fax for many of our Cloudli customers is that T.38 is real-time faxing while cloud fax is store-and-forward. That distinction matters particularly to businesses and organizations in sectors such as healthcare, government, and finance. Not only is fax used routinely in these industries to transfer sensitive data, regulations in these sectors demand the highest level of security and privacy protection – making T.38 the preferred option.

Here’s a simple breakdown of both real-time and store-and-forward faxing, along with a look at how the two are different:

Real-time fax – Real-time faxing serves as a direct conduit for data rather than containing an intermediary storage step. With real-time fax, there is an uninterrupted connection between the sending and receiving fax devices. This makes it easy to know for certain that faxes are transferring directly from a sending fax machine rather than from a go-between that is resending them. Transmission of real-time fax does not begin until the receiving side picks up.

Store-and-forward fax – Unlike real-time fax, cloud-based store-and-forward systems – as their name suggests – store fax data in an intermediary station before sending it on to the receiver. Unfortunately, having an extra agent between fax senders and recipients can compromise security, therefore it is recommended to avoid this type of middleman if possible – especially for senders that routinely transmit hypersensitive data.

When deciding between a cloud-based solution with store-and-forward fax, and one with T.38 real-time fax, it is important to consider all regulatory requirements that are applicable to your organization. For example, those organizations in the healthcare space need to be conscious of HIPAA requirements.

Real-time fax is accepted by HIPAA as a safe and legal form of document transmission. On the other hand, store-and-forward fax – which may be more susceptible to privacy breaches – is only HIPAA compliant with a signed Business Associates Agreement (BAA). This adds significant complexity to implementing the fax solution. Because this, it may be better for healthcare organizations to avoid store-and-forward fax and take the simpler route to HIPAA compliance. The same can be said for companies in other industries where privacy and security are paramount.

Right now, many businesses are looking to make changes to their fax solutions because they want to transition from their outdated PSTN to a digital solution. If this is you and your business, understanding the differences between cloud-based and T.38 fax is a must so you can choose the best fax solution for your needs. This eBook shares more useful tips and information for anyone who is considering switching away from PSTN to a more modern fax solution: Modernize Your Fax: Eight points to consider for a successful switch from PSTN to FoIP.

Finally, if you have questions about whether you are using the right fax solution for your business, get in touch with us. One of Cloudli’s fax specialists can provide you with a personalized fax assessment.

Tag(s): Fax

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