ADSL2, also known as G.DMT.bis or ITU G.992.3 is a fast type of digital subscriber line technology. Because it uses higher frequencies than communications like telephone calls do, it can transmit data much faster. This makes it ideal for consumers who want to get high speed internet service over their currently installed phone lines.
ADSL2 plans vary, but they all work using asymmetric DSL technology. This means that there is generally much more bandwidth on the consumer end than on the provider side. This translates to faster download speeds for consumers, but slower upload speeds. Actual line speeds vary along with the quality of the installed transmission lines. Because of improved signal processing techniques, however, ADSL2 speed typically exceeds ADSL speed while using the same amount of bandwidth, meaning it usually doesn't need additional line installations.
The maximum speed capabilities for this technology are usually around 12 Mbit/s when downloading and 3.5 Mbit/s when uploading. The ADSL2 standard regulates, however, that all ADSL2 broadband transceivers must meet a minimum of 8 Mbit/s downloading and 800 kbit/s uploading. The closer your ADSL2 equipment is to the service provider's network devices and the newer your phone lines are, the faster your access speeds will generally be.
ADSL2 coverage also comes in different flavors, called annex versions. These are different regional and operational modes that let your provider cater to different consumer needs. Numerous annex versions essentially mean that ADSL2 availability extends to consumers with normal telephone services, IDSN digital phone services and any other type of hard line communication. Certain annex versions work over longer distances, and some provide better upload speeds than others.
When you look at ADSL2, compare the differences in speed and data allowances first. Naturally, you'll want to find a provider who can guarantee quick downloads and uploads, but if your ADSL2 plan has a data allowance limitation, you'll only be able to do so much of either anyway.
Another important factor is contract length. Many providers offer great rates, but you're only eligible for them if you agree to sign a contract stating you'll use the service for a certain minimum length of time, which can range anywhere from 6 months to 2 years. It's also important to note that consumers with their own modems can save money but that these may not work as well with all ADSL2 providers.