Beta for FaxTap for SIP, an Important New FoIP Analysis Tool

Commetrex will begin a beta-test program in November for its latest fax-related product, FaxTap for SIP, which targets the lawful intercept and FoIP-analysis markets. General availability of FaxTap for SIP is slated for late Q4 with a single-seat license priced at $4250.

For years, fax-over-IP (FoIP) has been shuttered in the enterprise network where users have racked up major savings by avoiding the expense of fax boards and dedicated fax lines. But now, with SIP trunking becoming ubiquitous, enterprises are bypassing the gateway and sending faxes directly into carrier networks. This presents users, both subscriber and provider, with a whole new set of problems, problems that can only be solved with the proper tools, not to mention requirements for lawful intercept. That’s where Commetrex’ new FaxTap for SIP enters the picture.

FaxTap for SIP allows network operators and equipment vendors to analyze FoIP calls and render the image, even if the call uses the high-speed V.34 fax modem, and it does it for both G.711 pass-through and T.38 version 3 calls. We believe that this is the product the industry needs to finally move to reliable carrier-based FoIP. There is also an OEM-developer’s version that accepts PCM recordings directly.

The open-source Wireshark program has been and remains the industry’s pre-eminent SIP-analysis tool. But those that use it to help diagnose FoIP problems know that Wireshark’s analysis of a fax call can be misleading. For example, Wireshark incorrectly flags any RTP packets following a re-Invite to T.38 as “malformed T.38” packets. Moreover, it has problems handling T.38 version 3 calls with V.34. And, of course, Wireshark does not render the image or provide much in the way of T.30 analysis. FaxTap for SIP picks up where Wireshark leaves off.

FaxTap provides multiple levels of call analysis. The most basic is merely to render the fax image. The most detailed level provides a ladder diagram, listings of every T.38 frame, T.30 frame, and detailed image-line analysis. Low-level modem analysis can also be generated for all image-transfer modems, including V.34.

We are soliciting beta-test participants from the service-provider and IP-carrier industries. To learn more about the FaxTap for SIP beta, send us an email at, and we’ll send you a description of the program.

NetGen Launches Smart ACS

Smart ACS, based on OpenACS (Open Automatic Configuration Server), is an automatic configuration server that implements the “CPE WAN Management Protocol” (CWMP) specified in the Broadband Forum’s TR-069 specification. Smart ACS has fixes and modifications that allow OpenACS to work with NetGen’s Smart ATA, and is available under the GNU General Public License version 2.0 (GPLv2) free of charge to Smart ATA customers. NetGen will also provide a configuration service to customers that are not ready to bring the function in house.

One of the common problems with wide deployment of customer-premises equipment (CPE) in telephony is how to affordably and effectively maintain the software. But when thousands of CPE installations are involved, manual administration is impracticable. This prompted the Broadband Forum to release TR-069 in May 2004.

As its summary states, TR-069 is

A protocol for communication between a CPE and Auto-Configuration Server (ACS) that encompasses secure auto-configuration as well as other CPE-management functions within a common framework.

Smart ATA end users can always go to NetGen’s support page and download the latest firmware. But NetGen also offers a Smart ATA configuration-management service to all Smart ATA customers for a monthly service fee. And, for the Smart ATA customer with the scale to support bringing configuration management in house, NetGen offers Smart ACS software free of charge (after all, it is open source).

Smart ACS has the flexibility to support the service provider’s segregating CPE by subscriber class, for example, those that have enabled FoIP would receive a different configuration from those that have not. Of course, NetGen uses the same feature to segregate by customer, allowing customers to brand the ATA’s configuration homepage with their own logos.

Smart ACS will be generally available following its beta test, which begins in early November.

Want to stop saying “Keep your POTS for fax” to your subscribers? Visit the NetGen website or call 770-449-7704.

Smart ATA … Now with Smart FoIP

Smart FoIPSmart ATA, the industry’s only analog telephone adapter (ATA) with V.34 FoIP support, is available from NetGen Communications. Smart ATA now has Commetrex’ patent-pending Smart FoIP® fully integrated into the firmware. We’ve already received terrific feedback on the performance of Smart ATA, but now that it has Smart FoIP, it can live up to NetGen’s claim that it is the only ATA the really works for FoIP.

As we’ve discussed here before, Smart FoIP addresses two of the most common causes of FoIP call failures: late T.38 re-invites and PCM clock sync problems. Since carrier-based FoIP calls begin as a voice call, the two endpoint terminals can “hear” each other as soon as the connection is established. At that time, they begin executing the T.30 fax protocol. But if the two gateways are late (over six seconds) in attempting to switch to T.38, they will unwittingly kill the fax if the calling gateway does not have Smart FoIP. And PCM clock-sync problems are history since Smart FoIP makes every multi-page fax as reliable as a one-page fax. If that’s not enough, Smart ATA is the only ATA with support for V.34, and it also functions as an IAD and IP-PSTN gateway!

To learn more about Smart ATA, visit the NetGen Communications website or call 770-449-7704.

Join Us in Austin for ITEXPO West

ITEXPO West 2012ITEXPO, which is billed as “the world’s largest communications and technology event,” is coming up again on October 3-5. We’ll be there in booth 722 with information on Smart ATA – now with Smart FoIP fully integrated – and our newest products: Smart ACS and FaxTap for SIP.

If you’ve never been to ITEXPO, it’s a great opportunity to network and learn about the latest communications solutions for your business. And, in addition, Mike Coffee, Commetrex’ CEO, will be speaking on the panel Why Cloud Is Key to Your UC Deployment at the Cloud Communications Expo, a collocated event.

If you haven’t registered, do it today and join us for some fun in Austin. Questions? Email

G.711 FoIP Failures: It’s Not for the Reason You Think!

When your subscribers say, “I can send a single-page fax with good reliability, but multi-page faxes are unreliable,” it’s not usually due to dropped packets. Even if you and your carrier partners support T.38, not all faxes will end up switching to T.38, remaining instead in G.711 pass-through mode. No matter what you do, you’re going to have FoIP failures if you get a burst of dropped packets in G.711 mode. But when is the last time you saw a Wireshark extraction of the PCM where packet loss was reported? In today’s networks, it’s rare, but failures of a G.711 pass-through FoIP call are, unfortunately, not rare.

It’s caused by PCM clock-sync problems.

Over the PSTN, the clocks in a fax-receive modem are synchronized to the PCM clock in the transmitter with a phase-locked loop, so clock differences are not a problem. But in FoIP systems, the clock in the receive modem for the on-ramp/calling gateway, which is bringing the modem-image bits into the system, is different from the gateway’s system clock, which is driving the T.38 image packets out to the IP network. So there’s the possibility of a gateway either running out of bits to send, possibly (depending on the gateway) causing the transmit modems on the receiving gateway (SIP peer/off-ramp gateway) to run dry, or the buffers in the calling gateway will overflow, causing the call to fail, depending on whether the sending-endpoint terminal’s clock is slower or faster.

If both clocks use a 50-PPM oscillator, the worst case difference is 100-PPM. So, if the gateway starts with a 200-msec jitter buffer, it may get eaten up in 32 seconds, which is the image-transfer time of many one-page faxes. And if the buffer is not initialized between pages, there will be a problem on the second page.

But if the transaction is G.711 pass-through, how would the gateway know that the fax is between pages, allowing the buffers to be initialized? Commetrex, in a patent application filed in November 2010, disclosed a method of doing so. If you’re interested, the application has been published by USPTO as serial number US-2011-0109936-A1.

Want to know more? E-mail us at