How It Works: Cable Modems

How It's Sold: Cable Modems

Cable is ahead of DSL in deployment--more than 1 million people currently surf the Net over cable, and another 32 million living in Net-ready cable markets could if they wanted to. Forrester Research predicts that about 20 million people will use cable to access the Internet by 2003, compared to about 8 million DSL subscribers by the same year.

For now, cable Internet access is restricted primarily to home users; cable companies didn't wire downtowns or business parks, so many businesses are out of luck. In most markets, service costs from $30 to $40 a month, although in some areas the cheapest access will cost $70. Downstream speeds at those price levels range from 256 kbps to 512 kbps. But the faster you want to go, the more it will cost: 2 mbps downstream, 1 mbps upstream runs upward of $500 a month in some places.

You first need to find out if your local cable service offers Internet access. If it does and you want to get set up, be aware: Unlike DSL and standard modem service, cable service gives you no choice in ISPs. Time Warner cable systems, for example, work only with a provider called Road Runner; AT&T works only with Excite@Home. Cable companies have been reluctant to open their wires to unaffiliated ISPs, claiming they've invested too much in the system to lease the lines to other companies. ISPs have filed lawsuits to gain access to the lines, and they've won some local cases, which the cable companies have appealed. AT&T has recently softened its stance, announcing that it's willing to share its lines with other ISPs, though that won't likely happen until 2002.

On your end, you'll need an Ethernet-equipped computer and a cable modem. The modems are produced by a number of companies, including 3Com, Motorola, and General Instruments. Some cable companies rent modems and include the fee in the monthly service charge; others require you to buy them for about $200 to $300.

At this time, it's best to get a modem through your cable company. Different cable companies use different modulation schemes, and your modem must use the same scheme used by the cable company. While an industry standard called Data Over Cable Service Interface Specification has been approved, it won't be fully implemented for another year or so. When DOCSIS is universal, you'll supposedly be able to use any modem you want.

A cable service technician may need to install your modem and a splitter. If you already subscribe to cable television, you need a splitter to separate the lines to the television and the computer. You can order cable Net access without having a cable television connection, but some companies will charge more for that arrangement.

For additional information, take a look at the sites for the Cable Modem University and CableLabs.

Michael Gowan is a staff editor for PC World Online.