DSL (Digital Subscriber Line) is an always-on internet connection that ends in a socket on your wall, that looks much like a phone socket. The same housewiring does indeed carry phone and data! DSL is billed per month. Whether you use it for email once a day, or you are a net addict and use it constantly, your bill is always the same. Once you have a DSL line, you can use the entire resources of the internet, in the same way as you did from a regular modem, except you can use them 24 hours a day, with no connection delay, and usually (although not always) without a 'username' and 'password', and without a busy signal or any connection/disconnection process. The key advantage of DSL over modem is speed. DSL is from several, to dozens, of times faster than a modem connection. A complex web page that could take up to a minute to finish loading, can appear in just seconds over DSL. Connection speed, reliability, and the 'always-on' nature of DSL, are the main reasons it is so popular. For small businesses, DSL is also a great way to save money compared to pay per minute ISDN data, or expensive T1 lines.

Cable modems are typically faster for downloads than most if not all DSL lines, when the cable infrastructure is new or well maintained. However, cable has a few disadvantages to DSL. The first disadvantage is that cable is an RF network -- this means that it is vulnerable to transient problems "within the network" from RF interference. Since cable is a shared media, there is a possibility that performance may degrade over time as additional households plug in, connect additional devices (videos, game machines) to the TV lines. A cable company may react slowly to decreases in performance, as they never sell access by speed, or promise consistent speed or latency. One of the largest disadvantages of cable over DSL is the upstream (return path). Cable companies are using a very narrow band for return signaling, below all the space allocated for TV channels. This band is prone to RF interference and is very limited in capacity. Upstream transmissions may therefore compete with others in the area, get delayed (suffer high latency) due to noise fighting techniques, and cable Terms Of Service typically prohibit any kind of constant upstream use. Internet use is shifting away from central servers broadcasting to many individuals and some interesting peer to peer applications are appearing (games, voice and video applications, communual libraries). These applications need a strong upstream channel. In summary, cable modems are currently good value and strong competition for residential casual use, often available more cheaply and far faster than their ADSL competition. However, DSL is probably the more future-proof system, offering digital direct from the internet infrastructure. DSL lines are available for a wide variety of purposes, both business and residential.

Right now, your choice is probably going to be either SDSL or ADSL. ADSL is generally available more cheaply than SDSL. ADSL is designed for the home user. (RADSL is a slight variation on ADSL, which supposedly offers a longer reach). If you are going to be operating servers I would suggest SDSL if you can get it, not only because the maximum upstream speed is generally faster than ADSL. VDSL is DSL delivered over fibre to some lucky lucky people.

If you have heard even something about DSL, you will have heard about distance. Your phone lines normally terminate at a telco office, usually nearby. This distance, (the length of your line between your location and the telco office), is a very important factor in whether or not you can get DSL, and what speed you can get. Here are some rules of thumb for distance ranges. Please be aware that especially with non Telco ADSL lines, distance limits for speeds can vary widely from company to company. There are cases where it is policy for "residential" DSL lines not to be offered as far out as functionally identical "business" products!

You can use a laptop with DSL almost as easily as a desktop. Instead of an internal modem, or ethernet card, you need to buy a PCMCIA card supporting 10/100 ethernet (if your laptop has no ethernet port on it). They are a little expensive. The other option is to select a USB DSL modem when getting a line (if your laptop has a USB port on it). Apart from the choice of ethernet PCMCIA card, or USB modem, everything else is the same as a desktop DSL connection.

This really matters on the phone company and the speed rate that you signup for. It has been known to take anywhere from 10 - 60 business days.