Why is DSL better than a dialup connection?

• Speed
  Typical downstream DSL speed is 768 kilobytes to 1,500 kilobytes per second, roughly 25 times faster than standard 56K V.90 (or newer V.92) dialup modems.
  
  
• Always on
  Because it is either always connected, or connects very quickly, DSL is more convenient than having to dial up with a conventional modem. In addition, ADSL prevents other use of a telephone line.
  
  
• Latency
  DSL signals have much less transmission delay than dialup signals. While that difference in delay doesn't make much difference when surfing the Web, it can make a big difference in real-time gaming over the Internet.

Can you get it?

To get DSL, you must qualify, which generally means that you must meet the following conditions:

1. DSLAM availability
   There must be an installed DSLAM that can service your telephone line, and the DSLAM must have an available port.
   
   
2. Range
   Your premises must be no than 14,000 to 17,000 feet (depending on the flavor of DSL, the provider, and the condition of your telephone line) from the DSLAM, measured along the telephone line (not as the crow flies).
   
   
3. Load coils
   These devices, used to improve voice quality on longer cable runs, interfere with DSL signals. Removing them is often possible, but the telephone company may be reluctant to do so because of the cost.
   
   
4. Bridge taps
   These are branches in the telephone line. When a given telephone line is switched from one subscriber to another, that may be done by splicing on a new cable run in a kind of "T" or "Y" configuration, where one leg is then left unused. That unused leg degrades the DSL signal. Bridge taps can be removed, but again the telephone company may be reluctant to do so because of the cost.
   
   
5. No DAML or pair gain
   If the telephone company runs low on available copper telephone lines due to unforeseen demand, pulling new cable is so expensive that the telephone company will often use a DAML (digital added main line) or pair gain device to multiplex more than one service in a given copper line. DSL will not work with these devices. To get DSL, you need a dedicated copper line, which may not be available.

How do you qualify?

You can find a list of potential DSL providers in your area and do a rough check on whether or not you qualify for DSL, at the following online services:

• DSLreports.com
• Getspeed
• 2Wire

Bear in mind that these services are not perfectly accurate. The only sure way to check for DSL availability is to contact service providers directly. Even so-called pre-qualification from a service provider may not be accurate -- the only way to know for sure is to have your line tested.