There are two main types of DSL that basically differ concerning their streaming rates. The rates vary because customers have different needs (whether a higher upstream rate and lower downstream rate or equal rates for both) depending on whether this service caters to a household, or a small and medium size business.

Asymmetric

      ADSL. This stands for Asymmetric Digital Subscriber Line. Asymmetrical variations include: G.lite ADSL (or simply G.lite), RADSL, and VDSL. This type of broadband communication technology offers the transfer of high data rates in just one direction. This asymmetric data stream, with much more going downstream to the subscriber and much less coming back. ADSL is configured to deliver up to six megabits (Mbps) of data per second (6000K) from the network to the customer, which is up to 120 times faster than dialup service and 100 times faster than ISDN (Integrated Services Digital Network). This type of DSL is found predominantly in commercial use for business and residential customers around the world where general Internet access and applications where downstream speed is very important, like video-on-demand.

      G.lite ADSL

     G.lite is a medium bandwidth version of ADSL developed for the consumer market segment. This technologhy allows Internet access at up to 30 times the speed of the fastest 56k analog modems. It delivers up to 1.5 Mbps downstream and 384 Kbps up, is less expensive compared to a full-rate ADSL, does not usually require a splitter, and is easier to install.

      RADSL

     Rate-Adaptive Digital Subscriber Line. This technology is a variation of ADSL that uses carrierless amplitude phase modulation, divides the available frequencies into discrete sub-channels and also maximizes performance by adjusting the transmission to the quality of the phone line while in use.

      VDSL

     Very High Bitrate Digital Subscriber Line. An asymmetrical DSL that delivers from 13 to 52 megabits per second downstream bandwidth and 1.5 to 2.3 megabits per second upstream.

Symmetric

      SDSL. This stands for Symmetric Digital Line Subscriber. Symmetrical variations include: HDSL, HDSL-2, SHDSL, and IDSL. This technology provides the same bandwidth in both directions, upstream and downstream. This means that whether the customer is uploading or downloading information, you have the same high-quality performance. SDSL provides transmission speeds of up to 1.5 Mbps at a maximum range of 12,000-18,000 feet from a central office, over a single pair copper wire. This technology is ideal for smaqll and medium sized businesses that have an equal need to download and upload data over the Internet.

      HDSL

     High Data Rate DSL. This variety was created in the late 1980's and delivers symmetric service at speeds up to 2.3 Mbps in both directions. This fixed rate application, which is available at 1.5 or 2.3 Mbps, does not give standard telephone service over the same line. HDSL uses two or three copper pairs. 1.5 megabits per second in each direction over two phone lines, or 2 Megabits per ssecond over three.

      HDSL-2

     High Bitrate Digital Subscriber line II. This is a descendant of HDSL. This technology offers the same performance over a single phone line. This variant delivers 1.5 Mbps service each way, supporting voice, data, and video using either ATM (aynchronous transfer mode), private line service or frame relay over a single copper pair.

       SHDSL

      State of the Art, industry standard symmetric DSL. This means that the same rate via telephone line is sent back and forth from the customer. This variety achieves 20% better loop-reach than older versions of symmetric DSL, it causes much less crosstalk into other transmission systems in the same cable, and multi-vendor interoperability is facilitated by the standardization of this technology. This technology can operate at different bit rates, varying from 192 kbps to 2.3 Mbps, which maximizes the bit-rate for each customer. SHDSL is best suited for data-only applicatiions that need high upstream bit-rates, and is expected to be very well-suited to many business customers.

      IDSL

     Integrated Services Digital Network. This is a variant of SDSL that upholds symmetric data rates of up to 144 kbps using existing phone lines. This technology is different in the way that it can deliver services through a DLC(Digital Loop Carrier: a remote device often placed in newer neighborhoods to simplify the cable and wiring distribution from the phone company). ISDL differs from its relative ISDN (Integrated services Digital Network) in the aspect that it is always an "always on" service, but can use the same terminal adapter or modem used for ISDN.