Tap to Read ➤

How does DSL Work

Loveleena Rajeev
Digital subscriber line transmits data over the wires of a local telephone network and provides the user with high speed Internet connectivity. Learn more about this technology in the following story.
Originally, telephones were produced to allow the exchange of voice information with other phone users, using an analog signal. The same technique is followed to transfer data using a modem. A modem is used to transfer digital information, by demodulating the analog signal.


DSL technology allows the digital data to be transmitted directly to your computer. However, if one wants, the signal can be split to allow some of the bandwidth, to transmit analog data along with digital data, so that one can use the telephone and computer at the same time, while using the same line. This modern technology allows both analog and digital signals to be transmitted, making maximum use of the telephone lines' capacity.
Most users are connected to an asymmetric digital subscriber line (ADSL). This line divides the available frequencies, because of which users can download or upload unlimited information. It uses two equipment; one at the Internet service provider's end and the other at the customer's end. The user has a transceiver at his location and the service provider has a DSL Access Multiplexer (DSLAM) at his end, to receive user connections.
The Transceiver, also known as the DSL modem or an ATU-R, is the point, where data from a user's computer or network is connected to the digital subscriber line. The DSLAM gathers all the connections from different users and fuses them into a single, high-speed connection to the Internet.
DSL speed is described in terms of bandwidth rating, which has a range from 1.5 Mbps to 3 Mbps. The number 1.5 Mbps refers to the maximum bandwidth available for downloads, whereas the second number, 3 Mbps refers to the maximum bandwidth available for uploading.


  • DSL is cost-effective, as it requires no new phone lines.
  • The speeds on offer are higher than a regular modem.
  • It is easy to operate and install.
  • It is emerging as a standard for high-speed connectivity.
  • Internet and telephone can be used simultaneously.
  • Computers connected using digital subscriber line are less susceptible to theft or data destruction.
  • Different providers have many different packages, that one can choose from.


  • Digital subscriber line service availability is determined by the distance between the user and provider's central office.
  • Currently, there is no standardization of the modem, which means that the users may need new equipment to stay connected.
  • The service is easily available in urban areas, but not in rural areas.
  • Receiving data (downloading) is faster than sending data (uploading).
  • It is incompatible with fiber optic lines.
Digital subscriber line uses the existing telecommunication system to provide the users with better and high-speed connectivity. A better service in this day and age that supports audio, video, and multimedia data, will definitely help the growth of business and provide the domestic users with global connectivity.