TMCnet - World's Largest Communications and Technology Community



tmc logo
September 2007 | Volume 10 / Nuber 9
Enterprise View

Seamless Migration of Fax into IP Networks

Fax technology has advanced dramatically from the days of the stand-alone, walk-up fax machine. Today’s network fax servers integrate directly into office productivity tools, such as multi-function printers (MFPs) and CRM systems to automate the delivery and receipt of fax documents in electronic format. In addition, production fax servers can be used to automate business processes such as sending invoices, receipts or receiving purchase orders directly to an ERP system.

The increased focus on business process automation and document management, combined with the growing popularity of enterprise VoIP networks is driving many businesses to consider IP fax solutions. Migrating fax communications to VoIP architectures has many advantages over traditional fax, but can also raise concerns about reliability, bandwidth, and security. With the right IP fax implementation, these issues can be easily addressed.


Faxes are sent over an IP network using T.38, an ITU defined protocol for sending and receiving faxes in real-time over a packet network. However, it is important to note that within the data steam is the same ITU T.30 protocol that has been used to govern communication between fax machines for years. Although T.38 allows these T.30 packets to be transported across an IP network, fax termination point to fax termination point communication continues to be governed by T.30 when faxing in an IP environment.

Prior to T.38, packet loss in an IP networks was the biggest hurdle that fax over IP had to overcome. However, not all T.38 implementations are the same nor do they offer the same level of reliability. There are a few ways in which T.38 implementations can differ.

To ensure fax connections stay alive, T.38 endpoints employ an error recovery algorithm that transmits redundant packets. Sending redundant packets eliminates the risk that a fax session will prematurely terminate as a result of packet loss. In some T.38 implementations, the amount of redundant packets can be configured according to the local network conditions. This is an important feature because different networks or network nodes suffer packet loss to differing degrees.

A reliable T.38 implementation depends on a solid T.30 foundation. Just as all T.38 implementations are not the same, not all T.30 implementations are the same. T.30 implementations can differ greatly in performance and interoperability with all the different fax machines a company may need to connect to. It is important to look closely at a fax vendor’s T.30 implementation.


As with any IP-based service, the network should be provisioned to provide the necessary bandwidth, which may vary depending on usage patterns. Fax over IP is no different, however, it is important to note that a T.38 fax transmission typically takes much less bandwidth (pending packet redundancy settings) compared to simply sending a fax using G.711 VoIP. Furthermore, typical G.711 / RTP implementations are much more susceptible to packet loss compared to T.38. Unfortunately, such packet loss will result in dropped faxes, which is one of the biggest reasons why the industry is utilizing T.38 for fax over IP. More importantly, since a properly configured T.38 implementation can tolerate some packet loss, network administrators can continue to prioritize VoIP packets as a high priority via which ever QoS mechanism is currently in place.


In the context of the types of security threats facing organizations, there is a fundamental difference between intelligent fax platforms (boards or boardless) and competitive alternatives. Businesses today are concerned about three main types of threats to their network:

• Network Attack

• Privacy Infringement

• Content Attack

A network attack consists of a virus or malicious attack by a hacker. This type of attack in most cases is stopped by the network’s security infrastructure, such as firewalls and virus protection software. However, if a malicious packet does get through the firewall or is spawned internally by an employee, then an intelligent fax platform’s ‘fax only’ design can immediately recognize that it is a non T.4/T.6 or T.30/T.38 packet and drop it. Thus the malicious file, comprised of many non-conforming packets, will never make it into the host system to be propagated further throughout the network.

A privacy attack involves a fax being intercepted in transit by someone other than the intended recipient or fax machine. IP fax technology does not pose any additional risk to privacy because the IP portion of the fax traffic is contained within a properly configured and secure enterprise LAN/WAN.

The final type of attack is a content attack, in which the fax content is intercepted and altered. As with privacy infringement, migrating fax to IP does not pose any additional security threats. The fax travels over IP only over the enterprise LAN/WAN, which again would be protected behind a properly configured firewall or transmitted over a secure WAN connection such as a VPN. The public portion of the fax transmission would travel over the PSTN via T.30 and would be at no greater risk than if it were transmitted in standard PSTN format.

By taking just a few simple steps, businesses migrating to IP networks can achieve the same levels of security and reliability as traditional fax, with added cost and productivity benefits of IP fax. IT

Michelle Liro is Product Marketing Manager for the fax application market at Cantata Technology, the market leader in fax and fax-over-IP platforms. She can be reached at

» Internet Telephony Magazine Table of Contents

Today @ TMC
Upcoming Events
ITEXPO West 2012
October 2- 5, 2012
The Austin Convention Center
Austin, Texas
The World's Premier Managed Services and Cloud Computing Event
Click for Dates and Locations
Mobility Tech Conference & Expo
October 3- 5, 2012
The Austin Convention Center
Austin, Texas
Cloud Communications Summit
October 3- 5, 2012
The Austin Convention Center
Austin, Texas