ADSL is inching toward becoming the next big thing in high-bandwidth connectivity. It has the potential to bring as much as 7 Mbps of data across the copper telephone wires that are already installed in almost every home, and it is available today - almost.
Several vendors have ADSL devices in limited production, and at least one telephone carrier, GTE, has entered the second phase of real-world testing in the US. It is going to change the way we think about residential communications. Don't throw away your ISDN devices yet, though. ADSL is not generally available, and probably won't be for at least another year.
Any house with telephone service already has at least one pair of copper wires connecting the house with the telephone company's central office. The wires have gotten thinner, but the capacity and performance of the wires has not changed significantly since 1887.
What's changing is how the capacity of these wires are used - or unused. As plain old telephone service was developed, technicians determined that the human voice could quite faithfully be reproduced in about 3000Hz of spectrum. The copper wires themselves are capable of carrying signals in a much broader range of frequencies. This is where ADSL comes in. It can operate on the unused portion of your telephone line (the part above 3000Hz), and provide 6 Mbps of bandwidth in one direction and 640 Kbps in the other.
"This isn't just doing everything much faster. It's fast enough that you can change the way you actually do work remotely," said Paul Blair, a telecommuting Microsoft employee and one of GTE's current test users. "It's like being on the LAN."
Unfortunately, unless you work for a test site like Microsoft, Duke University, or one of the vendors building hardware, it's difficult for the consumer to run ADSL - at least for now. The telephone companies aren't prepared for it yet. There are no ISPs to connect to. The hardware is not easy to find.
The major stumbling block preventing ADSL from being on the market today is at the telco level. Telephone switches in central offices will need to be upgraded. Paula Reinman, who is working on Pacific Bell's ADSL project, said about 45 percent of Pacific Bell customers will be able to use ADSL by year's end.
There probably won't be many independent ISPs providing ADSL service. The consumer is most likely going to have to use one of his local telephone carriers as an ISP. But by the time ADSL is deployed, there should be competition for local phone service in most major cities.
It is possible to run ADSL today, although the process will most likely involve a number of vendors. If you can purchase the hardware required, and can arrange for a "dry pair" of copper wires between two points, then you can run ADSL between them. This is a daunting process for even an experienced early adopter but a number of people have done it successfully. The early adopters of ISDN had to put up with a similar process.
Most people are willing to wait a little while though. The technology will stabilize, and the setup process will become easier. Fortunately, many won't have to wait long. Pacific Bell will start its trials in the San Francisco Bay Area in September. Other RBOCs are expected to follow by the end of the year.
