ADSL (Asymmetric Digital Subscriber Line or Asymmetric Digital Subscriber Line) is a technology based on the copper pair from the normal telephone line, converts it to a high speed line. Uses the frequency spectrum that are not used for transport of voice, and therefore, until now, were not used, thus opening a channel of data at high speed, allowing your time (thanks to this separation data / voice), to implement a flat fee for the transport of data (internet).

In the ADSL service, sending and receiving data sets from the user's computer via an ADSL modem. The data pass through a filter (splitter), which allows the simultaneous use of basic telephone service and ADSL service. Ie, the user can talk on the phone while browsing the Internet.

ADSL uses digital coding techniques that help to increase the performance of existing telephone wiring. To achieve these rates of data transmission, the ADSL technology provides three separate channels on the standard phone line.

1. Two high-speed channels (a data reception and transmission of data).
2. A communication channel for normal voice (basic telephone service).

The two data channels are asymmetric, ie not have the same data rate. The channel is receiving data faster than the channel of transmission.

This asymmetry, characteristic of ADSL can achieve higher speeds in a network-user, which is perfectly adapted to the information access in which normally the volume of information received is much larger than the messenger. ADSL allows speeds up to 8 Mbps network connection to the user and up to 1 Mbps in user-network connection.

The main advantages of ADSL are:

1. Simultaneous use of Internet and telephone / fax, through the same telephone line.
2. Always Online. Connection to high speed Internet.
3. Flat rate Internet connection.
4. Access to services and broadband content.
5. Increased safety.

It is very difficult to find a DSL modem in trade, service providers included with the ADSL connection.