December 1999

Fax Is Not Dying — But It Will Admit Change

BY BROUGH TURNER

With the growth of the Internet and e-mail, some people wonder how fax can survive. But the 1999 Pitney Bowes Fax Usage Study found that fax is still alive, and that it is still the method of choice for many types of communications. Moreover, the study shows that fax is still growing, albeit at a slower rate.

Fax, however, isn't just growing. It is also changing. And change provides opportunities for those who are alert. In this column, in September 1998, I discussed some nascent fax technologies, namely, T.37, T.38, and Internet Printing Protocol (IPP). These technologies are now emergent, so it is time for an update.

T.37 — FAX OVER IP VIA E-MAIL
T.37 is an International Telecommunication Union (ITU) standard for transmission of fax over the Internet using existing e-mail protocols. Of course, this implies a new kind of fax machine — one that connects to the Internet, instead of or in addition to the PSTN. The T.37 standard has been released, and interoperability testing has been successfully completed among several companies. And, recently, a new kind of T.37 IP fax machine has appeared from several major vendors, including Panasonic. These machines plug into Ethernet and transmit faxes to like-minded equipment, wherever e-mail can reach.

Sending faxes via e-mail is a lot cheaper than using the telephone network. If a corporation is connected to the Internet, the incremental cost of sending a fax over the Internet is zero — all fax-related long-distance phone charges are eliminated.

T.37 transmissions occur at the speed of the Internet connection, which for most corporations is much, much faster than the 14.4 Kbps of traditional fax. Although Internet transmissions are typically faster, e-mail confirmation may be delayed.

Of course, there is an interoperability issue. There are only a few tens of thousands of the new IP fax machines versus more than 100 million traditional Group 3 (G3) fax machines, with 15 million new G3 machines sold in 1998 alone. In order to connect to traditional fax machines, the new machines must have either two interfaces (T.37 and traditional G3), or they need access to a gateway or “on-ramp/off-ramp” function.

An off-ramp is a system capable of receiving e-mail with MIME attachments (Multipurpose Internet Mail Extension for fax) from a T.37 fax machine or a PC that is destined for a G3 fax machine on the PSTN. The off-ramp detaches the MIME attachment, extracts the phone number of the destination fax from the addressee information of the e-mail, and sends the fax over the PSTN to the G3 device. The MIME attachment is defined in the T.37 specification to be a TIFF-S (Tagged Image File Format profile S) formatted document.

On-ramps accept calls from traditional G3 fax machines and send the resulting fax images to the appropriate Internet recipient as a MIME attachment to an e-mail. For example, there are service providers, such as eFax, that will give you with a free fax telephone number in North America and send you, via an e-mail, any faxes received at that telephone number.

T.38 — REAL-TIME FAX OVER IP
So what about the over 100 million conventional fax machines that might want to take advantage of the Internet to reduce long-distance phone charges? This has already become a big business using proprietary fax-over-IP techniques. Now, the ITU has developed the T.38 standard to provide a common approach.

Why can’t these systems just use T.37? The problem is how to provide positive delivery — the key advantage of fax. With traditional fax, that is, G3 fax using the T.30 protocol over the PSTN, you know when the transmission is complete. The sending fax machine tells you a document has been received at the other end.

The same effect is provided with T.37 fax, although not quite so quickly, by an exchange of e-mails. But when you forward a traditional fax over the Internet, there is no way to get a message back to the sending G3 fax machine, except by completing the whole transaction within the time limits of the T.30 fax protocol on the sending fax machine.

T.38 defines a protocol for use between IP fax gateways. A typical system takes traditional T.30 fax from the PSTN, routes it over an IP network, and then converts it back to a T.30 fax session at or near the destination fax machine. The system includes the following functions:

• Demodulate incoming T.30 fax signals at the transmitting gateway.
• Translate T.30 fax signals into T.38 Internet fax protocol (IFP) packets.
• Exchange IFP packets between transmitting and receiving T.38 gateways.
• Translate T.38 IFP packets back into T.30 signals at the receiving gateway.
• Modulate T.30 signals and transmit to the destination fax machine.

Systems using T.38 are usually transparent to the traditional fax machine user. The dialed telephone number may be different (going to a gateway first), but the system behaves normally, and (if all pages are processed without error) you know the fax has been delivered to the destination.

The T.38 standard is complete, and a lot of vendors are advertising it. However, as I write this, no vendors have demonstrated their ability to interoperate using the T.38 standard. The first interoperability testing was scheduled for late 1999 but has been postponed until April 2000. So T.38 is not quite real yet, but it’s very close.

OTHER IP FAX SOLUTIONS
In situations where IP bandwidth is not a major issue, it makes sense to just pass 64 Kbps telephony data (containing the 14.4 Kbps fax modulation) directly over the IP network. This is known as G.711 PCM over IP because the basic 64 Kbps telephony encoding is governed by ITU standard G.711. In other words, you can avoid the hassle of T.38 if you take the PCM samples from the telephone network at 64 Kbps, wrap them up as G.711 in IP packets, ship them over the Internet or private IP network, and put them back together again on the other side.

Since you’re directly passing the telephone PCM data from PSTN to PSTN over IP, you don’t realize any bandwidth savings, but you also don’t have to handle fax modulation or fax protocols. You can just let the PCM data flow through, and the T.30 protocols in the fax machines at each end talk to each other.

This approach may make sense in a voice over IP gateway, if most traffic is (compressed) voice and only an occasional fax must be handled at 64 Kbps. It may also make sense for some of the emerging fiber-based carriers in North America, who have low-cost bandwidth and may not bother to compress either voice or fax traffic before transmitting it over their IP networks. However, if bandwidth is precious, as in most of the world, then T.38 is the way to go.

TRENDS IN TRADITIONAL FAX
Is traditional fax doomed? Hardly. With 100-plus million fax machines, it will take a decade or two to effect a noticeable transition. For now, expect an increasing share of the fax traffic to be routed over IP using T.38. Sales of new T.37 IP fax machines will grow, but their widespread adoption requires both Internet connectivity — still hard to get in many parts of the world — and off-ramp services that allow the new IP fax machines to communicate with traditional fax machines.

V.34bis
A few years ago, sales of new fax machines moved from 9600-baud models to 14.4 Kbps fax machines. Now, the next generation of fax modulation is appearing — V.34bis (33 Kbps). These machines sold in small quantities in 1998, but projected sales in the year 2000 are over 1 million units.

V.34 fax is not only faster, but has more robust fallback modulation than that of the V.17 (14.4 Kbps) machines. Robust fallback is especially useful on telephone lines of poor quality. Even if a V.34 fax machine cannot operate at its full speed of 33 Kbps, it may be able to transmit at 15 or 19 Kbps during fallback, where a corresponding V.17 fax machine would fallback to 9600 or 4800 bps. So, within a year or two, V.34 will be the standard for most new fax machine sales, especially in developing countries.

Color Fax
Color fax was once touted as the next big deal. But color fax machines will not be sold in great volume. The few color fax machines available today are actually multi-function machines, that is, printers with fax capability. And the Internet Printing Protocol (IPP) by the IETF (RFC 2565-2569) is emerging as a better way to go for remote color printing.

Internet Printing Protocol (IPP)
IPP provides a standard way to print to a remote printer, and receive a status report from that printer. IPP has the potential to replace even T.37 as the way an IP fax is delivered. There are issues around finding the address of the destination printer and getting rights to print on that printer, but once those issues are resolved, IPP could be deployed fairly rapidly.

No new hardware is required, only new software drivers. For example, if Microsoft began providing IPP print drivers in Windows, then IPP-based printers could grow from zero to a huge market in less than 24 months. At that point, T.37 fax would likely be displaced by upgrades to IPP-based fax, as IPP is a printing protocol, and thus more flexible than T.37 or T.30 fax.

PLENTY OF OPPORTUNITY
Fax continues to be a growing market. New fax technologies are available for PSTN-based fax, and new Internet-aware devices are appearing on the market, but they are all fax machines. Don’t expect the simplicity of fax — just put the paper in and dial — to ever lose appeal. Do expect a 10 to 20 year transition from the PSTN to the Internet, including several dramatic changes along the way. And look at these changes as opportunities for the CTI industry to create new services in this converging world.

Brough Turner is senior vice president of technology at Natural MicroSystems, a leading provider of hardware and software technologies for developers of high-value telecommunications solutions. For more information, call Natural MicroSystems at 508-620-9300, or visit the company’s Web site at www.nmss.com. E-mail to the author ([email protected]) is also welcome.