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High Speed Internet » What Is Dsl

What Is DSL?

DSL – or Digital Subscriber Line – is a type of high speed internet access that is provided using existing telephone lines and associated infrastructure. The only limitation to DSL is that the consumer needs to be close to the internet service providers (ISPs) office.

With DSL, the consumer needs to purchase or lease a special modem – usually available from the ISP – which will transmit and receive the internet-based voice, video, and data. The special DSL modem connects to the existing phone lines already installed in the user's residence or place of business.

How DSL Works

DSL works by taking the regular phone line and dividing the frequencies into two bands. The low-frequency band (lower than 5 kHz) is used for voice data, such as regular phone conversations. The high-frequency band (above 24 kHz) is used by the ISP to transmit information from (downstream) the internet and to (upstream) the internet.

There are specialized phone jacks available, which most consumers choose to install, that allow a single phone line to be used, simultaneously, for voice and internet connection, with no interference or bleed over from either. Therefore, it is possible to have a conversation on the phone and to be surfing the internet at the same time, using the same phone line, with DSL.

DSL Options

Currently there is a wide range of DSL options available to the consumer, depending on location and the consumer’s connection needs:

  • ADSL (Asymmetric Digital Subscriber Line) – has two different speeds of transmitting information, usually much faster downstream (from the internet to the consumer) and slower upstream (from the consumer to the internet). Transmission rates are up to 1 megabits per second (Mbps) for upstream transmission and up to 8 Mbps for downstream connections.
  • VDSL (Very High Speed Digital Subscriber Line) – can transmit information at high speed rates of up to 100 Mbps, supporting high bandwidth activities such as high definition television and internet-based telephone services.
  • RADSL (Rate-Adaptive Digital Subscriber Line) – the upstream connection speed varies or adapts to the phone line connection, to provide a better quality downstream service; this service works well for when the consumer is not close to the ISPs office.
  • IDSL (ISDN Digital Subscriber Line) – a form of DSL that bypasses the ISPs central office equipment and carries the data over a regular data network as opposed to the voice network.
  • HDSL (High Data Rate Digital Subscriber Line) – developed in the United States, this DSL option uses two regular telephone lines to create the capacity for 1.5 Mbps internet connections and can be expanded to three lines for speeds up to 2.0 Mbps.