From the Enterprise VoIP Experts

September 02, 2009

SIP Forum's Fax-over-IP Interoperability Task Group Reaches Key Milestone

By Group Managing Editor, SIP Trunking Report

Fax-over-IP, or FoIP, is seeing strong adoption in the enterprise space, as it helps companies lower their communications costs, boost employee productivity, improve customer service, increase security, adhere to regulatory compliance rules and reduce their carbon footprint.

FoIP has numerous advantages over traditional fax. First and foremost it helps companies cut their communications costs, as it uses VoIP, or Voice-over-IP technology for transmission of faxed documents. That means companies no longer need to use traditional phone lines to send and receive faxed documents. Not only does FoIP allow faxes to be sent over the public Internet, or dedicated network, it also greatly reduces transmission time. Anyone who has used traditional fax is aware of how long it can take to scan, send, and then print a multi-page document over regular phone lines.

With FoIP, documents are sent as attachments to recipients’ email inboxes – however unlike regular email these attachments are secure and verifiable. This means users no longer need to get up and down from their desks in order to send and receive faxes (this helps save time and boosts employee productivity). In addition, FoIP enables users to send and receive multiple faxes simultaneously.

Another important advantage is security: With traditional fax, documents often sit at the fax machine for all eyes to see – whereas with FoIP, only the intended recipient can open and read the faxed document.

Yet another key advantage of FoIP is that it is a true green solution: Unlike traditional fax, where every page of every document is printed, scanned and printed again, the user decides whether or not to print the received document. This helps companies save considerably on paper and toner costs. It also helps companies save considerably on energy consumption: Unlike traditional fax, where you need to have a fax machine on every floor, of every office, or perhaps for each and every department, FoIP can be facilitated using single fax server that delivers faxes organization-wide. And because traditional fax machines are more mechanical in nature (they have electric motors, scanners and many moving parts), they tend to use much more energy than a server-based system.

But the adoption FoIP has not been without its challenges. As with many communications technologies that are still in their infancy, there are interoperability issues that still need to be worked out. Incompatibility between FoIP systems has resulted in reliability issues and has slowed adoption. This, in turn, has put mounting pressure on FoIP solutions providers (including software and hardware manufacturers) and industry standards bodies to develop specifications that will solve the problem of system interoperability.

At the heart of this challenge are inconsistencies in the implementation of the SIP and T.38 protocols. Basically, SIP is what enables different IP fax systems from different manufacturers to establish a connection and “talk” to each other. Meanwhile the T.38 protocol is what facilitates the actual transmission of the data across the network in real time.

Just because two IP fax systems utilize SIP – which, by the way, is a well-established IETF standard – doesn’t necessarily mean they can interoperate. That’s because SIP is actually a set, or “stack” or protocols that work together to facilitate the set-up and tear-down of IP sessions. And when the protocol stack is developed for a specific SIP-based solution, the developers are not necessarily all on board with each other, in terms of striving for interoperability between systems.

According to Alan D. Percy of AudioCodes, one factor that makes SIP interoperability difficult to achieve is the way the IETF Requests for Comments (RFCs) are developed. As opposed to the traditional ITU specifications that have been around for decades, “IETF RFCs and drafts are developed in an open and communal environment, using committees and consensus to craft the specification,” Percy writes in his blog on TMCnet. “This has very many positive benefits, but also a few predictable negative side effects. The problem is that the RFC that defines SIP has become ‘everything to everyone’ and bloated in both size and in flexibility.”

As Percy explains, because the language in the latest version of the specification RFC 3261 from the IETF Network Working Group is intentionally filled with “weak” terms (such as “may,” “can,” and “option”) the standard itself comes under a wide array of interpretations from developers. This results in a “very loose specification that allows the developers of SIP-based systems to make plenty of decisions on features of functions. The byproduct of this is that two systems can be completely RFC 3261 compliant and completely incompatible.”

For example, he points out that, under the current standard, “there are no fewer than five ‘correct’ ways to transport DTMF tones from one end point to another.”

As Percy points out, however, this is “only the tip of the iceberg.” In additional to the technical challenges of SIP interoperability in IP fax there is also the “politics” of which developers, and which vendors, get to establish the “true” standard that is used.

“It appears to me that soon after the authors of RFC 3261 finished their work, the fun really started,” Percy writes on his blog. “As the development teams of the various product and application companies started to build their solutions based on RFC 3261, the looseness of the specification allowed them to make wildly different choices all ‘within specification.’ The result was that you had developers that had invested untold hours of hard work into developing a protocol stack that worked fine in their own lab and with their own products, but had serious interoperability issues with other vendors. To each of the developers, it appeared that ‘everybody else screwed up.’”

To help address these problems, the SIP Forum, and industry group dedicated to the advancement and continued development of the SIP protocol, formed the Fax-over-IP Interoperability Task Group, which is charged with investigating ongoing issues with the deployment of fax services, specifically ITU T.38, in SIP networks.

As explained by Marc Robins, SIP Forum president and managing director, in a recent release, "A key goal of the SIP Forum FoIP effort is to bring together researchers, engineers, equipment vendors and service providers to exchange ideas, share experiences, and propose approaches to address FoIP technology issues and problems. Of course, a key focus is on the use and applicability of SIP to address systemic or architectural problems."

“In addition, if the initiative identifies concrete proposals to improve FoIP that would require modifications to the underlying protocols, the Forum will forward these proposals to the appropriate groups in the standards bodies, including the IETF, IEEE, or ITU-T,” Robins said.

The Fax-over-IP Interoperability Task Group reached a key milestone this week when it published its formal FoIP Problem statement, which outlines the key challenges hindering the adoption of FoIP which the group has chosen to address. Some of the issues include:

--Interoperability failures seen in the field or lab
--Reliability or quality issues seen in the field or lab
--Deployment experiences
--Development experiences
--Architectural principals
--Proposals for achieving a higher degree of FoIP interoperability and/or FoIP reliability
--Proposals for soliciting additional real-world feedback from implementers and service providers

“It is only through the efforts of the group as a whole that we have reached this important milestone,” said Neil Weldon, director of technology, CTO office, Dialogic Corporation, who serves as the FoIP Task Group Chair. "We now turn our efforts into addressing these problems to improve the overall FoIP environment for all across the industry and we are open to new interested parties getting involved in these efforts."

To download a copy of the problem statement, click here.

The FoIP Task Group leadership includes Neil Weldon; Max Schroeder, Sr. VP. Faxcore, who serves as the Task Group Whip; and document editors including Mike Coffee, CEO/COB, Commetrex Corporation; Michael Chen, LSI Corporation; Kevin P. Fleming, director of software technologies, Digium, Inc; and Mike Oliszewski, CTO, FaxBack, Inc.

Active FoIP Task Group participants include representatives from companies including Alcatel-Lucent, AEMcom, AT&T, AudioCodes, Biscom, Dialogic Corporation, Digium Inc., C4U Solutions, Cisco Systems, Inc., Commetrex Corporation, Comunycarse, DevFoundry Software, emFAST, Faxback Inc, Faxcore, Lexmark, LSI Corporation, NeuStar Inc,, Nortel, Omnitor, Orange, Packetizer, Sagem-Interstar Inc., Siemens Enterprise Communications Group, Sonus Networks and Teridian Semiconductor Corp.

FoIP Task Group participation also includes Eric Burger, chairman of the board, SIP Forum, and Richard Shockey, chair of the technical working group.

In related news, the SIP Forum -- which is presenting numerous sessions during ITEXPO West 2009 in Los Angeles this week -- announced today that membership in the association continues to grow. Currently, the group has 48 full member companies, five academic members, and more than 6,500 individual members from around the world. Companies that recently joined include Bell Canada; 8x8, Inc.; Optimum Lightpath, a division of Cablevision Systems Corporation; Cedar Point Communications; Comcast Cable; Cox Communications; Genband, Inc; NET; Nortel; PAETEC; Samsung Electronics Co., Ltd.; ShoreTel Inc.; and XO Communications.

“The continued industry support and resulting growth in membership -- especially from service providers, and thought-leadership within the academic and research community -- is a huge vote of confidence that the work the Forum is engaged in continues to be highly relevant to the success of SIP- based products and services in the commercial marketplace," Burger said in a release.

Robins added that "All of the Forum's various initiatives are gaining significant industry traction, including ‘SIPconnect’ which provides a ‘best practices’ methodology for accomplishing trouble-free, SIP trunking between SIP-enabled IP-PBXs and SIP-enabled VoIP service providers; the Fax-over-IP (FoIP) Interoperability Task Group work focused on achieving a higher degree of FoIP interoperability and FoIP reliability; and the User-Agent Configuration Task Group effort to develop a simple configuration mechanism and profile suitable for a variety of user agents.”
“In short, the progress we're making in these areas is having a positive, direct effect on our membership,” Robins said.

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Patrick Barnard is a contributing writer for TMCnet. To read more of Patrick’s articles, please visit his columnist page.

Edited by Patrick Barnard