According to the ADSL Forum (www.adsl.com), a leading online resource for all DSL issues, DSL is defined as "a modem technology that transforms ordinary phone lines (also known as twisted copper pairs) into high-speed digital lines for ultra-fast Internet access."

In other words, this technology will allow people to gain access to the Internet at very high speeds using the existing phone lines that currently run into nearly every home and business in the US.

This is accomplished by using a different frequency spectrum beyond that of your current voice or analog fax communications. This means that not only do you get the fast access over your current line, you can still fax or talk on the phone at the same time.

Before we go much further, let's discuss the basic terms and the different types of DSL you should be aware of.

DSL, as we mentioned before, refers to the general technology of digital subscriber lines. And, as you will see, there are a number of different types of DSL, all of which are collectively referred to as XDSL.

ADSL, or asymmetrical digital subscriber line, is currently the most common type of DSL. It is asymmetrical in terms of data transfer rates. That is, the downstream traffic is much faster than upstream traffic.

This brings us back to the point of the frequency spectrums mentioned above. The phone line can be thought of as being broken down into three different channels: a high speed channel to your home, a medium speed channel from your home and the analog voice or fax signal on the third channel.

For most Internet uses, this works very well since your upstream request for an html file is very small but the downstream results of your request (pictures, graphics, sound, video) are all, comparatively, very large. Phone companies are claiming downstream rates to be 8 Mbps and upstream at 1.5 Mbps (still about the same as a T-1 line).

Another common name heard when discussing DSL technologies is G. Lite. This is also know as DSL-Lite or Universal DSL (UDSL). A year or two from now, when DSL is available to the masses and you can go to your local computer store for a DSL modem, we will be using G. Lite technology. G. Lite is simply a toned-down consumer version of DSL allowing for 1.5 Mbps downstream and 384kbps upstream transfers. And, G. Lite requires a minimal amount of setup and installation to get up and running in your home or business.

The last form of DSL worth mentioning is VDSL or BDSL. This is a commercial version of DSL used by companies needing very high speed transfer rates. In fact, VDSL is rated at 52 Mbps downstream (the equivalent of more than 34 T-1s) and 13 Mbps upstream.

As I have mentioned throughout, DSL uses your existing phone line. However, there are a few other things you need to know in order to implement the service.

First of all, you need to be within 18,000 feet or less (about three or four miles) of your local telephone company's central office. Incidentally, this only covers about half of the US.

Second, if you live that close to your local telephone company, your computer will need to have a few pieces of hardware. The normal phone line coming out of your wall will plug into the DSL modem. This modem will cost up to $200 and should be supplied by your access provider. From there, a network cable will run into your computer. This means it will be necessary to have a Ethernet Network Card (NIC) built in to your PC.

And, lastly, there is the cost. G. Lite will be priced to compete with cable modems at around $40 to $80 per month. Faster DSL connections will start at $100 to $200 per month for business applications.

Like cable modems, DSL is not yet available in the Yuma area. However, of the three major broadband technologies, I believe that DSL will be the dominant choice in Yuma and across the United States within the next two years.