ADSL sends digital data over standard twisted-pair telephone lines, which makes the technology attractive for users in homes or older offices. ADSL service improves or declines in relation to the users' distance from the phone company's central office. Nearby customers can reach speeds of 9Mbps for data downloads and 640Kbps for uploads. For customers on a circuit's fringe, however, the download speed could drop to as low as 1Mbps and uploads to no more than 16Kbps. On the down side, cable modems work in a sort of party-line arrangement.
Encryption allows the modem to receive the essential data and ignore the rest of the clutter.
But encryption can't keep the network from bogging down as traffic increases, an increasingly troublesome problem as more cable modem users come online. According to statistics compiled by The Yankee Group, a Boston-based technology research firm, more than 1 million cable modems are currently active worldwide, predominantly in the United States, compared with just 250,000 ADSL connections. Ruth Chatterton, an Internet consultant with TeleChoice Inc., a telecommunications industry research firm located in Owasso, Okla., believes that telcos still have an opportunity to close the market gap between ADSL and cable modem services. Both have comparable features and will move closer in cost in the next few years. The final outcome is anything but clear at this point.