March 24, 1997

Up Periscope
56K modems are here ... well, sort of
By Bill Machrone

  Coming soon to a neighborhood near yours! 56K-bps modems! But not necessarily your neighborhood. You can take one home from the store today, but whether it works or not is a toss-up. While U.S. Robotics and Motorola are claiming that 75 percent of U.S. phone lines will support 56K-bps connections, an ongoing, hands-on test comes up with a total closer to 55 percent.

Frank Derfler, PC Magazine's intrepid connectivity editor, is spearheading a test in which PC Magazine editors and labs staff are testing 56K-bps modems from as many different parts of the country as they can. I'm one of the data points. I've been dragging a laptop and a Courier V.Everything x2 modem to friends' houses all over New Jersey, hooking up to their phone lines and seeking dial-up nirvana. More than half of the lines I've tested have delivered. Sadly, my own analog phone lines are among the losers that can't connect at 56K bps.

Officially, I don't care, because I have an ISDN line. But I certainly care if this technology is being oversold. And you certainly care if you're hoping to get single-B-channel performance from an analog modem. You might get it and you might not. I've only used U.S. Robotics' V.Everything x2 modem so far, so my experiences are limited to this one product. What I've discovered is that the modem has excellent diagnostics and can tell you exactly how fast it's communicating and how well it's able to use the bandwidth of your phone line.

By the way, 56K is just a figure of speech. FCC strictures on line modulation limit the speed to 53.3K bps. Still, the performance is far superior to a 28.8K-bps modem and is indistinguishable from a single-channel ISDN connection when browsing the Web.

In my testing, I used the analog breakout line from my 3Com Impact IQ ISDN terminal adapter as a reference. Since the analog-to-digital conversion was right there on my desktop, the chances for attenuation were minimal. I consistently got connections between 48K and 53K bps, and the line was clean and quiet, with all of the audio bandwidth available. My analog phone lines only managed 22K- and 24K-bps connections, and the diagnostics showed heavy attenuation at the higher end of the frequency spectrum.

At a friend's house, I got connections between 44K and 48K bps on both of his lines. His property abuts Bell Laboratories, and the central office is just down the street. If he doesn't have good phone lines, nobody does. Other friends' lines yielded similar results. I limited my tests to home lines because the PBX at your office or in a hotel probably prohibits an x2 connection.

After talking with product managers at U.S. Robotics, I took the modem and laptop to several neighbors on our street, since we all have underground phone lines and the houses are roughly the same age. I wanted to see if anybody had better lines than I did. They didn't. In fact, a couple were worse. One thing's for sure: Nobody will be selling 56K-bps modems in this neighborhood.

Should you take the plunge? I think so. ISPs are adopting 56K-bps technology, the competitors are moving toward a unified standard or at least interoperability, and if your phone line is clean enough, you'll love the throughput.

Bill Machrone is vice president of technology for Ziff-Davis Publishing Co. He can be reached at

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