Now, Isdn For Dummies

New easy-to-use high-speed adapters even have spare phone and fax jacks

About 18 months ago, I plunged into the world of digital telephones when I set up a link over ISDN (integrated services digital network) circuits between my home and my office. It took hours of pondering obscure manuals and many tech-support phone calls before I got the Motorola terminal adapters--the ISDN equivalent of modems--working right.

How times have changed. A few weeks ago, I plugged a card called the Supra NetCommander ISDN from Diamond Multimedia (800 727-8772 or into a slot in my Windows 95 PC. I followed the instructions on the screen when I turned the machine on, loaded some software off floppies, and within a few minutes was cruising the Internet at 128 kilobits per second.

PRICE DROP. Last week, I talked about the steps that vendors are taking to make it easier to get ISDN service. This week, I'll look at the hardware that is making ISDN very practical for telecommuters or anyone who wants fast access to the Net. At $299, the Supra NetCommander is the cheapest and easiest route to ISDN I have found. But companies such as U.S. Robotics and Motorola are fast catching up in the ease-of-use department, and prices have dropped by about one-third in the past year.

Like modems, the new ISDN terminal adapters come in both plug-in card and external versions. But the choice is more important than it is with modems. External adapters connect to computers through serial ports, which are limited to a top speed of 115 kbps. This means their speed limit is quite a bit slower than ISDN's 128-kbps maximum. On the other hand, externals don't require opening your computer. And, of course, only an external can be used with Macintosh (which lags far behind Windows in ISDN support). All of the devices discussed here include at least one standard telephone jack for a phone or fax machine. In fact, you can make or receive a fax or a voice call while an ISDN call is in progress. Your data rate will drop to 64 kbps, but that's still far faster than the widely used 28.8-kbps modems.

The $375 Sportster ISDN 128K from modem giant U.S. Robotics (800 550-7800 or is similar to the NetCommander. The main advantage is its very thorough software for tracking ISDN calls and troubleshooting problems. When ISDN works properly, which is most of the time, calls connect silently and almost instantly. But when something goes wrong, it can be nearly impossible to figure out why. The Sportster comes with extensive diagnostics, including one that tests connections to the phone network every time you start your computer.

SENSITIVE. The Sportster's big brother, the Courier I-Modem, combines an ISDN terminal adapter with a conventional 28.8-kbps fax modem. Ordinary terminal adapters can only call other ISDN devices. So while you might use ISDN to cruise the Net, you may still need a conventional modem to tap your office E-mail. When you place or receive a call, the I-Modem senses whether the other end is an ISDN or a conventional line and uses the proper circuitry. The I-Modem comes in a variety of configurations, starting at about $430.

Motorola (800 365-6456 or, which pioneered low-cost ISDN, offers the Bitsurfr Pro external and Bitsurfr PC internal adapters. The external models provide two analog jacks, so you can plug in both a fax and phone.

Getting ISDN is still somewhat more complicated than installing a modem. But with the latest hardware and plug-and-play software, it's a chore that anyone with average computer skills can easily handle. If you want to know more, join me at 8 p.m. EDT, Monday, June 17, in the BUSINESS WEEK Online chat room on America Online.

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