New phone lines put fire in your modem ISDN lines allow modems that run four times faster

Your computer

February 09, 1997|By MICHAEL J. HIMOWITZ

THE AMERICAN phone network is one of the greatest engineering feats in the history of mankind. Pick up the receiver, punch in a few numbers and a few seconds later, you're chatting with someone across town or halfway around the world.

While the system that hurls your voice across continents and oceans is state-of-the-art, the technology that connects it to your home hasn't changed that much in 50 years. It works fine with people on the line, but it wasn't designed for the millions of humans who suddenly want their computers to do the talking.

As a result, PCs with modems are starting to stress out local phone systems, and the phone lines that work so well when we speak have become bottlenecks for Web surfers and telecommuters who want to ride in the fast lane.

So what are the alternatives? While cable networks, direct satellite transmission and other exotica are on the horizon, the only one that's available to most users now is an ISDN line. It doesn't escape the phone network entirely, but it's fast and reliable -- if you're willing to go through the hassle and expense of getting it to work.

An acronym for Integrated Services Digital Network, ISDN dates back to the 1980s, when phone companies were looking for a way to leverage more capacity for business users from their existing copper wires.

To understand what ISDN does, consider what happens when you use your modem to dial another computer over a regular phone line.

Your PC and the computer on the other end want to exchange digital ones and zeros. There's not much variety in the conversation, but the transmission has to be accurate.

The phone network is digital, too -- except for the line that connects your house with the central office. It was designed to transmit the continuous frequencies of your voice. So your modem converts the PC's ones and zeros into high and low frequency tones. The phone system converts those tones into digital signals at the central office, sends them to the central office that serves your host computer, converts them back to audio transmissions and sends the signal to the modem attached to the other computer. That modem converts the tones back into digital ones and zeros. Whew!

Not surprisingly, something gets lost in the translation. The newest modems can transmit 33.6 kilobits of information per second -- the equivalent of 3,360 characters of text. But because of noise on the phone line, modems are often forced to reduce speed, and you'll rarely get a connection that fast. Even the 56 kbps modems due on the market in the next few months are unlikely to produce real-life communication at their theoretical top speed.

Enter ISDN, which bypasses the whole messy audio thing by making your phone part of the phone company's digital network. A single ISDN line provides two 64 kbps communication channels. You can use one for data and one for voice, or combine them for computer communications at 128 kbps. Thats about four times as fast as today's best modems -- and no noise on the line.

Sound too good to be true? You bet. ISDN service is difficult to set up, and it isn't available everywhere, particularly if you live more than 3.4 miles from a central office. Your Internet service provider or office network must have ISDN service, too. If your destination doesn't have ISDN, there's no point in setting up the line.

To make ISDN work, the phone company has to change the phone wiring outside your house, at the central office and sometimes in the lines along the way. You'll need to make changes to your home's internal phone wiring and spend $300 to $600 for a gadget called a terminal adapter -- a sort of digital modem designed for ISDN lines. Finally, you'll have to get your PC's software to work with all of the above, right down to the technical details of telling it what brand of switch your phone company's central office uses.

This can be a nightmare, and not all phone companies are willing or able to provide the help average users need. Bell Atlantic, one of the most aggressive ISDN marketers, will deliver the service anywhere that it's technically possible. And if you're willing to pay, it will handle the entire setup, from installing the line to configuring your PC.

Even so, it took five frustrating weeks to get my ISDN line installed and working a year ago. Company officials say they're a lot better at it now, and the latest terminal adapters are much easier to set up than mine was.

Then there's a matter of cost. In addition to buying a terminal adapter, expect to pay the phone company anywhere from $125 to $400 to set up your service, depending on how much hand-holding you need.

Monthly ISDN charges are usually higher than fees for regular phone service, depending on the phone company and state regulators. In practice, the fees vary so widely from state to state that you wonder whether we're all on the same planet.

In Arkansas, ISDN users pay as little as $18 a month for unlimited service. In some parts of New England, unlimited service costs thousands of dollars per month. In Maryland, Bell Atlantic wants approval for a sliding monthly scale that tops out at $236 for unlimited use. That's higher than most states, but if you're willing to settle for 140 hours a month (enough for all but the most frantic Web surfer) you can get it for $48. If you exceed the limit, you pay an additional 1 to 4 cents per minute, depending on the time of day and number of channels.

Is ISDN worth the money? As a heavy Web user, I love it, and lots of telecommuters swear by it. But I'm always willing to try something new -- and in future columns we'll talk about what's down the road.

Pub Date: 2/09/97

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