Fax and Telecom Testing Blog

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

2009-03-13T20:43:00Z

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 how well a particular fax device operates by emulating normal operation and error conditions for a wide variety of different fax devices, as both caller and receiver. FaxLab allows users to replace a room full of fax devices with software, saving time...(read more)

Fax Book and Free Test

2008-10-31T20:27:00Z

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 Amazon. Check it out! Shifting gears... Need to see if a fax works, but don't having anyone who can send you a fax? Check out the free service from HP that allows you to send a fax and then using inbound fax number returns a fax to you within 5...(read more)

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

2008-10-23T18:53:00Z

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 circuit had begun to make good on its promise to produce a bounty of affordable consumer electronics. This meant that fax machines could go from being arcane, proprietary and extremely expensive to commodities... if only their makers could get...(read more)

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

2008-10-23T01:26:00Z

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 G3" V.34 fax modulation was initially released as an integral part of the ITU T.30 protocol, it was implemented on a nearly proprietary basis. Two same make same model machines could communicate using V.34 but, otherwise, their call fell directly...(read more)

Fax Transmission Power — More Is Not Always Better

2008-10-09T00:43:00Z

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 to encounter diminishing returns of signal quality. For this reason, most transmission systems have published maximum power levels for the signals they are expected to carry. By the same token, there is a noise floor that limits the low end of the power...(read more)

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

2008-10-02T02:23:34Z

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 the task of creating such a standard in 1993. The ITU-T recommendations E.450 through E.457 define an objective quality measurement standard for Group 3 facsimile transmissions. This standard is implemented in QualityLogic's FaxLab test tool...(read more)

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

2008-09-25T02:01:04Z

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 0 of T.38 was approved over 10 years ago and with updates that have gone into version 2 has become a mainstay of FoIP-capable gateway designs. Version 3 brings compatibility with V.34 capable fax machines that have become both commonly available...(read more)

Comparing Fax Call Data From Different Sources

2008-09-19T01:16:41Z

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 has the ability to import fax call data from .wav sound files and .pcap WireShark data files. Several engineers have asked about the process of matching up the content of these files for analytical comparisons. This is a tricky proposition when there...(read more)

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

2008-09-18T17:36:14Z

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 of facsimile becoming the commodity service it is now go back to the late '60s and early '70s. The representatives of the then completely proprietary fax industry met to discuss the novel idea of interoperability between their products under...(read more)

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

2008-09-15T23:42:00Z

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 could not be guaranteed with packet traffic routing over the over the Internet, another standard, T.38, was created to relay traffic in a method consistent with the Internet's constraints. The new enabling hardware is a gateway that converts the...(read more)