How does ADSL compare to Cable Modems?
ADSL provides a dedicated service over a single telephone line; cable modems offer a dedicated service over a shared media. While cable modems have greater downstream bandwidth (up to 30 Mbps), that bandwidth is shared among all users on a line, and will therefore vary, perhaps dramatically, with traffic. Cable modem upstream traffic will in many cases be slower than ADSL, either because the particular cable modem is inherently slower, or because of rate reductions caused by contention for upstream bandwidth slots. The big difference between ADSL and Cable Modems, however, is the number of lines available to each. There are no more than 12 million homes passed today that can support cable modems, and while the figure also grows steadily, it will not catch up with telephone lines for many years. Additionally, many of the older cable networks are not capable of offering a return channel; consequently, such networks will need significant upgrading before they can offer high bandwidth services.