Reaching IP Telephony’s Full Potential
Testing SIPfaxEngine
Next-Generation FoIP

Reaching IP Telephony’s Full Potential

Our industry and the public have enjoyed the many benefits of IP telephony: costs are down, quality is up, and innovation and business formation are greater than ever. But there is plenty of innovative potential in IP telephony that, when tapped, will deliver unprecedented user value. We’re talking about moving beyond the tired paradigm of least-cost routing, and moving to smart routing,allowing users to control their call’s destination with a precision unavailable with today’s E.164 model. Smart routing, sometimes called service-based routing, will mean the value of any service that requires an all-IP route, such as HD voice and FoIP, to become readily accessible. And that unique value-adding service you developed can be discovered by your growing market.

Our perspective comes from Commetrex’ extensive background in FoIP. The industry suffers from call routing better suited to the industry of the last century. The age of IP telephony, at least as far as an FoIP or HD voice is concerned, are services that need an all-IP call route for optimum performance. For example, a FoIP call with a PCM segment can only run at modem speeds, not Internet wire speeds. Moreover, PCM-IP handoffs can be error prone, making the transition from pass-through to T.38 problematic. Additionally, HD voice cannot even be transported by the PSTN.

Knowing this, the SIP Forum developed IETF RFC6913, which was intended to improve FoIP call routing. However, we would be surprised if there has ever been a call routed over an all-IP route due to an RFC6913-specifed contact header. RFC6913 specifies the SIP.fax=”T38” and SIP.fax=”passthrough” media tags for use in an FoIP SIP INVITE.

RFC3840 specifies how to use media tags in the user-agent (UA) contact header to indicate the UA’s capabilities and, implicitly, how the call should be routed. RFC3841 defines SIP header fields: “Accept-Contact”, “Reject Contact”, and “Request-Disposition”, enabling a caller to specify what calls will be accepted or rejected, as well as the handling instructions for proxies.

Let’s not leave out ENUM, an elegant system for E.164-to-URI mapping, which, if fully implemented, would really take the industry to the proverbial next level. For more information, see “Techniques for Carriers’ Advanced Routing and Addressing Schemes” from the i3 Forum.)

So, it’s all there; we just need to use it. Contact Commetrex at 770-449-7775 to see how you can implement Smart FoIP® into your next-generation peripheral devices.

Testing SIPfaxEngine

Last year we announced SIPfaxEngine, which is now shipping. It’s the core technology needed to build a SIP-based fax media server. (There is still all the surround stuff of a server for the OEM user to develop.) But how does an OEM go about testing a server that supports hundreds of FoIP ports?
Well, we’ve got your back.

SIPFaxEngine Diagram2

Our SIPfaxEngine product includes an unlimited-port-count BladeWare license for testing. You also get a license to our FaxTap NG, which picks up where Wireshark leaves off in fax analysis and image rendering.


  • Commetrex’ renowned Multi-Modal Terminating Fax (MMTF)—T.38 V3 with full modem support including
  • V.34
  • 25-years-in-the-field T.30
  • SIP call control based on pjSIP with commercial license
  • IP V6
  • Parameter management
  • Selective logging detail
  • DTMF and RFC2833
  • Power Management
  • SIP Registration
  • Glare support
  • RFC 6913 support
  • In-band call-progress analysis
  • Per-call metrics
  • STUN
  • JBIG
  • Polling
  • Reports and logs
  • Flexible header/footer
  • Smart FoIP® (optional)
  • Configuration management
  • C# and C++ APIs

Thinking about rolling your own? Utilize the industry’s best technology and Commetrex’ productive development by contacting Commetrex today!

Next-Generation FoIP

The next-generation FoIP won’t really be worth bothering with unless it runs at Internet wire speed. Well, we figured out how to do it and a little more:

  • Wire-speed image transfer,
  • Full backward compatibility,
  • Complete elimination of today’s FoIP problems.
  • Real-time…no store-and-forward, and
  • Standards based

But without user-directed/smart routing, it ain’t gonna happen.