Fax Featured Article

Commetrex recently produced a white paper titled “The State of IP Fax 2011,” giving a good overview of that topic, including Fax over IP, especially with its discussion of where FoIP is today, how we got here, and where it’s headed.

What the paper calls “Phase I of enterprise IP-fax adoption” was its use in intra-enterprise applications, enabling enterprises to use their corporate IP networks to move intra-enterprise faxes between offices and within the corporate LAN.  Premises-located gateways were required to move the fax beyond the enterprise edge.

But, as the paper says, “we still had not been able to move the IP-based fax beyond the enterprise network. That required the industry to mature somewhat, to move to Phase II.”

Marking the graduation to Phase II, in 2005, the large-footprint IP carriers began to deploy their second-generation infrastructure. And the momentum continues to build as more IP-network vendors offer the necessary advanced technology, T.38, for both inbound and outbound -- and more recently some access-service providers began tentative support for T.38.

But as the paper does a good job explaining, “their long-haul peering arrangements were problematic because only some of their partners would carry a T.38 session. Special routing was required.”

And now, with IP carriers providing support for fax, “the push for direct SIP trunking has begun.” This is because SIP trunking allows enterprise equipment, such as IP PBXs and IP fax servers, and the IP-based access providers to directly connect without the need for the PSTN-IP gateways. No, SIPconnect is not a new “standard,” but even with the benefit of SIPconnect, “achieving interoperability can often be a challenge.”

As the paper shows clearly, “premises-equipment vendors and access-service providers must work together effectively to achieve SIP-trunking interoperability.  And access providers and IP-backbone providers must do the same... But all too often, the service provider’s attitude is that interop requirements are for them to know and the enterprise-equipment vendor’s responsibility to somehow figure it out and make it work.”

Which of course is a recipe for frustration and poor service. Commetrex officials say “significant practical problems” with SIP negotiations for FoIP calls exist in carrier-based networks, and have developed “Smart FoIP,” a technology that improves the reliability of fax-session establishment for media servers, ATAs, and gateways, to respond to the problem.  

The new technology can boost transaction success rates often by 10 percent, Commetrex (News - Alert) officials say, adding that Smart FoIP is included in BladeWare beginning with Release 3.0.

Commetrex officials say carriers have done a great job of virtually eliminating dropped packets, “but PCM clock-synchronization problems remain,” and that Commetrex’ Smart FoIP relay technology and BladeWare media servers include buffer-management technology that eliminates PCM-clock-synchronization problems in certain common sessions.  

So what’s on tap for Phase III? As Commetrex officials say, in 2011, “we have entered a phase of rapid adoption of IP-based fax in the enterprise.” They say enterprise users should “seriously consider” SIP trunking to simplify their network, or make sure that their new system is either all IP or capable of a smooth transition to all IP.

“The industry will soon leave the rough edges of the Phase I-to-Phase II transition behind as the backbone carriers move to their second-generation networks, usually based on Sonus GSX (News - Alert) gateways, which support T.38 fax with Commetrex’ technology.”

Phase III is depicted by the paper as “the effective use of FoIP in international tandem-network calls.” Commetrex officials say the SIP Forum (News - Alert) FoIP Task Group (primarily equipment vendors) and the i3 Forum FoIP working group (primarily international carriers) “have formed a testing cooperative that has characterized international FoIP performance.”