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Home > Applications > Fax > How Does Fax Over IP Work ApplicationsHow Does Fax over IP Work?Companies can achieve dramatic savings by integrating their fax servers with their VoIP network. Implementing an IP based fax server enables companies to:
For a more in-depth look at the technology and benefits of FoIP technology, see our FAQs on FoIP and our FoIP Security pages. Cantata – All You Need to KnowOnly Cantata offers Brooktrout intelligent fax technology supporting corporate networks in all stages of transition ranging from purely TDM, to hybrid, to pure VoIP networks. Both the Cantata Brooktrout SR140 and TR1034 fax platforms support real-time fax-over-IP, providing companies with the ability to integrate fax servers and fax document management solutions with their VoIP network, achieving the same high levels of performance, reliability and scalability that enterprises have come to expect over the past 20 years from Cantata while capturing the benefits of fax-over-IP. The Brooktrout TR1034 supports both TDM and VoIP networks, providing companies a smooth migration path from TDM fax to IP fax and a single platform to support and maintain company wide eliminating the hidden costs of maintaining multiple vendor platforms. If you’re looking for a corporate fax standard, look no further. The Brooktrout SR140 is a host-based fax-over-IP platform for companies that have made the transition to VoIP to integrate a pure IP based fax solution. SR140 is a software-only solution that requires no additional hardware. How Does Fax-over-IP Work?Understanding how faxes are sent over an IP network requires a basic understanding of the T.38 and T.30 protocols. T.38 is the protocol that describes the process for sending and receiving faxes in real-time over a packet network. T.30 is the protocol that describes the communication process between two fax devices on a circuit-switched network. For an Internet aware fax device, such as a fax board, to reliably send and receive faxes over IP, that device must support T.38. T.38 is designed to preserve the traditional fax experience and ensures faxes are successfully sent and received by making adjustments for jitter, latency and packet loss, which are inherent in all IP networks. Without T.38, fax devices, which are sensitive to timing, cannot reliably send and receive faxes over an IP network. The diagram below shows a typical real-time fax over IP implementation
with a Brooktrout based fax server sitting behind a T.38 gateway
that supports SIP or H.323 call control. While the gateway sits between the two fax end point devices, in this case a fax server and a fax machine, the faxing intelligence resides in the end point devices. As in traditional circuit switched fax technology, fax-over-IP devices are responsible for negotiating, synchronizing and communicating with each other. On the back end, the gateway sends and receives T.30 data wrapped in T.38 packets while in front it receives a traditional T.30 fax signal. The gateway recognizes the data as a fax and the repackages the data for consumption by both end points. T.30, the same protocol used for faxing over traditional circuit switched networks, remains at the heart of every IP fax connection with each end point requiring a high degree of T.30 interoperability. This is necessary since Internet aware fax devices must also be able to communicate with legacy fax devices. Where We Fit
Why Fax-over-IP? Why not email?With nearly 200 million fax machines installed worldwide businesses must have a fax strategy. Simply, facsimile technology is the preferred method for electronically transmitting an original hard copy document. Critical functional areas such as finance, legal, human resources, sales and procurement rely on fax to conduct their business. Demand for fax technology is not dependent upon the transport protocol rather it is driven by the business needs that fax technology fulfills. T.38 versus G.711 Pass ThroughWhile all IP fax devices must be interoperable, not all IP fax products are created equal. Some fax servers utilize the G.711 voice codec to transmit faxes over an IP network. Unfortunately, simply passing an analog fax signal through a codec designed for voice communication produces an unreliable result frequently failing completely. Faxing is a real-time synchronous technology, which is at odds with the asynchronous nature of IP networks. The fax process relies on tight timing tolerances. Latency and jitter, which are common in IP networks, poses a challenge for fax technology engineers. What may be tolerable for a voice conversation is not necessarily tolerated by a fax device. T.38 solves this problem with techniques like spoofing that keep the fax connection alive while fax data in transit catches up with the process. In order to achieve PSTN fax reliability that companies have become accustomed to, T.38 is a necessary requirement for serious fax applications. Security and T.38 Real-time Fax-over-IPThe Brooktrout TR1034 fax board is known in the industry as being the most secure fax board. Cantata continues this tradition with our fax-over-IP products. With a properly configured IP network, there are no additional security concerns with real-time fax-over-IP on the Brooktrout TR1034 or SR140. If a malicious packet penetrates the firewall, it will be dropped by the TR1034 and SR140. Brooktrout T.30 and T.38 protocols allow only for the transfer of T.4 and T.6 fax images. To protect against internal attacks, the IP network can be configured to use VPNs between the T.38 endpoint and gateway. What We OfferOnly Cantata offers Brooktrout-brand intelligent fax technology supporting corporate networks in all stages of transition ranging from purely TDM, to hybrid, to pure VoIP networks. Both the Cantata Brooktrout SR140 and TR1034 fax platforms support real-time fax-over-IP, providing companies with the ability to integrate fax servers and fax document management solutions with their VoIP network. With Cantata’s industry-leading fax technology, enterprises can achieve the same high levels of performance, reliability and scalability that they have come to expect over the past 20 years from their Brooktrout products while capturing the benefits of fax-over-IP. The Cantata Brooktrout TR1034 supports both TDM and VoIP networks, providing companies with a smooth migration path from TDM fax to IP fax. The TR1034 saves time by providing a single platform to support and maintain company wide, which can eliminate the hidden costs of maintaining multiple vendor platforms. For companies looking for a pure software-based IP fax solution, Cantata offers the Brooktrout SR140, a host-based fax-over-IP platform for companies that have transitioned their networks to VoIP. The SR140 has the same renowned functionality that has made Cantata the leading provider of intelligent fax boards, including our industry leading T.30 protocol, Error Correction Mode and MMR fax compression. The SR140 is available in a variety of densities from two to 60 channels. To add channels as their needs grow, customers simply purchase and install a new software license key to instantly upgrade their solution. There is no hardware to buy, maintain or upgrade, ever. With nearly 20 years experience since pioneering the intelligent fax technology category, Cantata has built a solid reputation for delivering the best value in the industry. We are committed to building on this legacy and continuing to deliver unmatched value as the world moves to an all IP network.
* Source: Davidson Consulting, 2005
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