Digital Subscriber Lines are sold either for the Home (Residential) or as a Business service. Business DSL is typically SDSL- Symmetrical DSL, with identical upload and download rates. It is considerably more expensive than DSL sold to the home. Home DSL, however, is nearly always ADSL- Asymmetrical DSL, with different rates for Upload (much slower) and Downloads (faster). ADSL is much less "predictable" than SDSL, and, although it is often faster on downloads, it is not generally sold as a business service.

ADSL service typically comes with only one TCP/IP address. (A TCP/IP address is a number that identifies a device as being unique on the Internet. Without this unique number, a device cannot be "addressed" by another device.) For a business seeking to use DSL as a gateway to the Internet, only one address is a significant limitation. Most ADSL connections (including those from Bell Atlantic) come without a permenant TCP/IP address at all- An address is "dynamically assigned when you need it" from a pool of addresses the company has. This makes it difficult to use the DSL channel for any incoming services without software tricks. (Such as dynamic domain name addressessing.) Any DSL link for business should include at least one permenant TCP/IP address.

   You must be reasonably close to the telephone company's Central Office to have a DSL connection at all. 15,000 feet can be considered a maximum range, or about five miles. This will cause problems for businesses in rural areas. If you are too far for any type of standard DSL connection, you may want to investigate other technologies: Cable modems from your local cable company, IDSL (DSL-type connections over an ISDN phone line), line-of-site high speed radio systems including Wi-Fi systems (some can be boosted to 20 miles), or Satellite downloads.

   DSL's advertised speeds are all MAXIMUM data rates. There is no MINIMUM data rate when connecting to the Internet on a DSL connection. DSL connections can be "oversold" by providers, causing performance to degrade considerably from the rated speeds. This tends to be more evident on ADSL (Home) connections than business SDSL links. With SDSL services, providers often guarantee that the data rate that is advertised will always be available to a customer.