Fax and Telecom Testing Blog

New FaxLab 7 Product for T.30 and T.38 Fax Interoperability Testing

Steve Kang — Fri, 13 Mar 2009 20:43:00 GMT

QualityLogic is pleased to announce a major upgrade to the FaxLab fax interoperabilty testing tool. FaxLab is used by device manufacturers, network equipment providers, and carriers to simplify the process of fax device compatibility testing. It tests...(read more)

Fax Book and Free Test

Jim Zuber — Fri, 31 Oct 2008 20:27:00 GMT

For those of you working with Fax of IP, an interesting book called "Fax, Modem, and Text for IP Telephony" was recently published by Cisco Press. This book covers both T30 and T38 basics, as well as much more. It has very positive reviews on...(read more)

What is NSF... and why should I care?

John Lunsford — Thu, 23 Oct 2008 18:53:00 GMT

In the late '70s, T.30 was created to make fax machines something they had never been before, interoperable. But many of their manufacturers wanted to go outside of T.30 and continue to use some of their non-standard tricks and abilities. The integrated...(read more)

V.34 to V.17 Can Be a Hard Fall

John Lunsford — Thu, 23 Oct 2008 01:26:00 GMT

Now that the V.34 compatibility battle is finally being won, a new problem has surfaced. How do two fax terminals that were attempting to use V.34 mutually decide to abandon it, fall back to V.17 and complete sending their pages? When the "Super...(read more)

Fax Transmission Power — More Is Not Always Better

John Lunsford — Thu, 09 Oct 2008 00:43:00 GMT

There is an article of faith among analog electronics engineers that, if you have to send a signal through difficult conditions, pumping up the power is a good, time honored approach to doing so. But, what about distortion? Somewhere power boosts have...(read more)

ITU E.450 Figure Of Merit – The User’s Point of View

John Lunsford — Thu, 02 Oct 2008 02:23:34 GMT

The dichotomy of fax protocol conformance versus interoperability becomes most pointed when it is necessary to gauge the performance of a fax terminal. A Quality of Service (QoS) standard is simply a necessity for this type of evaluation. The ITU undertook...(read more)

Version 3 of T.38 — It's Likely to be in Your Future

John Lunsford — Thu, 25 Sep 2008 02:01:04 GMT

Economic conditions being what they are, the Fax over IP (FoIP) user community is looking for an edge. V.34 'Super G3' fax, covered by version 3 of T.38, makes Internet fax transmissions really move saving money and bandwidth. The original version...(read more)

Comparing Fax Call Data From Different Sources

John Lunsford — Fri, 19 Sep 2008 01:16:41 GMT

How can data files that monitor the same test call but come from disconnected sources be directly compared with each other? In the Post Mortem Analysis of T.30 and T.38 Traffic posting, I pointed out that QualityLogic's DataProbe T30-T38 Analyzer...(read more)

Fax Conformance vs. Interoperability — How do you strike the balance?

John Lunsford — Thu, 18 Sep 2008 17:36:14 GMT

For years, fax device manufacturers have pondered the question of how much accommodation they should make for non T.30 compliant devices. Too little and customers complain about inability to send their pages, too much and development costs soar. The roots...(read more)

Post Mortem Analysis of T.30 and T.38 Traffic

John Lunsford — Mon, 15 Sep 2008 23:42:00 GMT

Facsimile traffic has followed voice traffic in its migration to the Internet. Historically, the T.30 protocol has been used to transmit facsimile messages over the traditional PSTN network. Because T.30 contained a variety of timing constraints that...(read more)