Definition of DSL
DSL, which stands for Digital Subscriber Line, is a service your local phone company can provide. It is often resold by ISPs (Internet Service Providers) in one of two flavors: ADSL, which is Asynchronous DSL and SDSL, which is Synchronous DSL. These two flavors involve the difference in download speed (the rate at which information you request from the Internet is sent to you) and upload speed (the rate at which information you transmit is sent to the Internet). Asynchronous DSL means the two speeds are different, with the download speed typically much faster than the upload speed. Synchronous DSL means both the upload speed and download speed are the same.

Service Considerations
Typically ADSL is offered to consumers because their main use of the Internet is browsing and e-mail. SDSL is commonly marketed to businesses because they are more likely to have content on a Web server or an e-commerce server that will need to be uploaded to clients via the Internet.

Installation Details
DSL arrives at your premises over a regular phone line. You do not get a separate bill from the phone company, as the ISP pays for the phone line and bills you for "Internet Service." There is typically a minor installation charge that includes a "DSL Modem," which is actually a router, to connect you to the Internet.

Service Options
DSL service is offered at several speeds, requiring you to select the one most closely matching your needs. The low end starts at a download speed of 200kbps (kilobits per second), which is about 4-5 times faster than a regular modem. For an office of four people doing occasional Internet browsing and e-mail, this is fine. If the Internet is more central to your business and requires that all of you be online for a good part of the day, consider 400kbps or 700kbps. If you plan on having a Web server at your office, make sure you subscribe to aDSL.

DSL Service Limitations
There is a distance limitation in order to achieve these fast speeds over a regular phone line. The phone company's CO (Central Office) must be less than 15,000 feet from your office (about 3 miles). If you are located in a suburban or rural area, DSL service may not be available at all.

DSL Service Costs
A sampling of costs from around the nation shows that ADSL service with 700kbps download and 128kbps upload runs between $50 and $70 per month. Depending on the phone company or ISP contract, this line may be restricted to a single user, with higher prices for a corporate account. Currently HMC charges $19.95 per month for DSL and Verizon charges $37.50. Combine these two charges to get the total monthly cost. SDSL service of 200kbps is around $180 per month with 700kbps running around $350. There is typically no limit to the number of users that can share an SDSL line.