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DSL Nuts and Bolts

DSL uses the idle frequencies of the existing copper phone lines in your home or office. Unlike cable modem service, which your cable company probably provides in only one form, DSL comes in several types--each with distinct advantages and disadvantages. Two you need to know about are ADSL and G.Lite. The latter is a variation on ADSL that computer-savvy users can install by themselves. The A in ADSL means that the line is asymmetric--data arrives on your computer (downstream) at a faster rate than it goes back out (upstream).

Most people will need fast download speeds for pulling music and image files off Web servers, among other uses. Unless you're uploading massive files to a service bureau or sending big files from home to the office, you probably won't need a superfast upstream speed.

If you're a business user and must have fast uploads, look at SDSL.

It's a symmetrical DSL connection that provides the same speed in both directions. You'll pay more for the connection, but you may also get it installed more quickly than you would an ADSL line. That's because vendors selling SDSL bypass the waiting lists by renting lines from the phone company.

Both ADSL and G.Lite have two terrific assets going for them. The first is price. You can grab an ADSL connection for between $30 and $50 a month, depending on your location. If your timing's right, you might pull off a coup and get a free DSL modem and installation. For instance, at press time, Pacific Bell, Southwestern Bell, Nevada Bell, and Ameritech were promoting just that: $40 per month with free installation and DSL modem.

Check for specials by watching the Web site of each DSL vendor in your area.

The second key feature after price--and the clincher for me--is that both ADSL and G.Lite let you use one phone line for simultaneous voice calls and high-speed data access (SDSL connections accommodate data only). Saving the cost of an extra phone line for a dial-up modem is enough to justify getting DSL.

High-Flying Speed

Here's how to understand the numbers and put them in perspective. Your clunky analog modem lumbers along at 56 kilobits per second. Typical upstream DSL rates range from 128 to 384 kbps, potentially almost 7 times faster than your old modem. Downstream speeds are measured in megabits per second; a 1-mbps line--1000 kbps--is almost 18 times faster.

ADSL speeds are usually advertised as 384 kbps for downstream and 128 kbps upstream. Those are the guaranteed speeds, but they are sometimes way faster because ADSL can theoretically handle speeds of up to 8 mbps for downloading and roughly 800 kbps for uploading. (G.Lite is slower, with its downloads topping out at about 1.5 mbps and its uploads at 384 kbps.)

DSL providers can guarantee such speeds because they're selective about their customers. Most will accept orders only if you're within a specific distance from the central office. For instance, Pacific Bell and US West want customers to be within 17,500 feet of the CO, while Bell Atlantic's limit is only 15,000 feet.

To determine the limits DSL providers set on distance from the central office, check the DSLreports distance chart.

The sweet spot for a perfect ADSL connection? Less than 12,000 feet from the CO. But if you're less than 17,500 feet from the CO (G.Lite supports 18,000 feet), you'll still be in good shape. The farther you are from the CO, the slower the speed. Once you get past about 22,000 feet, you're heading for DSL never-never land. Don't forget, though, that there's still cable modem or satellite--or a moving van. You can check whether you're close enough to qualify for DSL by going to the DSLReports.com, site. After you enter your street address, it tells you whether you're within the allowable distance from the CO and estimates the maximum speed you can get. But only your DSL vendor can determine your exact distance from the CO.

Pick a Provider

Before choosing a DSL provider (most are ISPs) check with the comp.dcom.xDSL newsgroup and listen to what other DSL users are saying. Read the news at The List. the premier DSL resource site. Consider picking up David Angell's DSL for Dummies(IDG Books, $25, 1999). Then dig deeply into the resources listed in "Online Resources."

For a comprehensive list of DSL providers in your area, check out Internet.com's Telocity

Local phone companies are obligated to allow third-party companies--known as Competitive Local Exchange Carriers--into their CO. Covad, Rhythms, NorthPoint, and other CLECs rent the "last mile" of copper lines--the distance from the CO to your home or office--from the telephone company. CLECs usually partner with Internet service providers, and consumers generally deal with the ISP, not with the CLEC.

Some ISPs use Point to Point Protocol Over Ethernet connections. PPPoE makes your DSL connection work like a dial-up account. You'll still have a perpetual connection, but to get onto the Internet, you'll need to use a dialer once a day.

To compare ISPs' monthly rates for DSL in your area--and to read both glowing and scathing customer reviews--check out the2wire

If you're computer savvy, consider installing the DSL kit and kaboodle yourself. Many ISPs will waive the installation charges. DSLReports charges $25 to ship a do-it-yourself kit--modem, filters, cable, and software--and offers a 30-day service guarantee.