Introduction to DSL for Business Internet Service

DSL - Digital Subscriber Line technology
DSL - Digital Subscriber Line technology.

DSL is a well-known form of residential broadband internet services. It has remained one of the most popular home Internet options for many years as providers continue to upgrade their network infrastructure to increase speeds. Many of these same providers also offer Business DSL services to corporate customers.

Why Business DSL is Different

Most home DSL services use a form of the technology called asymmetric DSL (ADSL). With ADSL, most of the network bandwidth available on an Internet connection gets allocated to downloads with relatively less bandwidth available for uploads. For example, a home ADSL service plan rated for 3 Mbps supports download speeds up to 3 Mbps but typically only 1 Mbps or less for upload speeds.

Asymmetric DSL makes good sense for residential networks because the normal Internet usage patterns of consumers involve frequent downloading (to watch videos, browse the Web, and read email) but comparatively less frequent uploading (posting videos, sending email).  In businesses, however, this pattern does not apply. Businesses often generate and consume large amounts of data, and they also cannot afford to wait long for data transfers in either direction. ADSL is not the best solution in this scenario.


The term SDSL (symmetric DSL) refers to alternative DSL technologies that, unlike ADSL provide equal bandwidth for both uploads and downloads. Originally developed in Europe in the 1990s, SDSL gained an early foothold in the business Internet market many years ago. DSL technologies in those days normally required installing a pair of telephone lines to separately manage upstream and downstream traffic. SDSL was one of the earliest forms of DSL to work with a single phone line. An early form of high-speed SDSL called HDSL (high data rate DSL) required two lines but was later made obsolete.

SDSL possesses all of the common characteristics of DSL, including an "always on" combination of voice and data services, availability limited by physical distance, and high-speed access compared to analog modems. Standard SDSL supports data rates starting at 1.5 Mbps with higher speeds offered by some providers.

Is Business DSL Popular?

Numerous Internet providers around the world offer business DSL service plans, often in multiple tiers of price and performance.  In addition to SDSL packages, some larger providers (particularly in the U.S.) are also able to offer higher-speed ADSL packages also, leveraging the infrastructure they have built for their residential customers.

Business DSL remains popular for some of the same reasons as residential DSL Internet:

  • The use of ordinary telephone lines makes DSL easier to install than other forms of Internet service where separate cable runs are often required
  • Wireless Internet options have not yet advanced to the stage where they offer the right combination of cost, reliability, and speed