What is DSL

DSL stands for Digital Subscriber Line. It is a technology that allows high speed internet connections over traditional telephone lines. Due to certain technological difficulties (distances and equipment.) not all areas can have DSL; however, regional telephone companies are improving this situation rapidly. Prices range from $20 up to $80 for service depending on speeds and accessibility.

How does it work?

DSL makes use of the existing telephone line by splitting the line into multiple channels. Voice service remains at the low traditional frequencies (0-20kHz), while data is transferred over much higher, unused, frequencies (26kHz-1.1MHz).

How is it different than cable?

The key difference is that DSL is a direct line to the network, while cable is a shared resource. The result is that cable can maintain theoretically higher bandwidth, however, as more subscribers sign up that bandwidth is consumed, thus effecting all customers. DSL is constrained by distance, but seems more "future proof" than cable technologies. The quality of either depends heavily on the individual ISP.

How are ADSL and SDSL different?

ADSL and SDSL are the two common forms of commercially available DSL. ADSL (Asymmetric Digital Subscriber Line) means that the upstream and downstream bandwidths differ. For most residential customers ADSL is advantageous because most traffic is downstream. SDSL (Symmetric Digital Subscriber Line) means that the upstream and downstream bandwidths are equal. SDSL is useful for commercial applications, such as web servers, where there is a significant upstream traffic.