What is DSL?
DSL stands for Digital Subscriber Line, a broadband technology that uses telephone lines and digital coding to create a connection to the Internet from your computer. That link can carry vast amounts of voice, video and data information at very high speeds.

How does DSL work?
DSL service providers use the same copper-based lines that let you make and receive telephone calls. To send data at high speeds carriers use the lines at higher frequencies that telephone service doesn't need. DSL modems are connected at both ends of the line. The modems digitally divide your telephone line into three channels: one for telephone traffic, one for upstream data from your computer to the Internet and the third for downstream data traffic from the Internet to your computer.

I understand that there are several forms of DSL service. What are they?

ADSL, HDSL, IDSL, SDSL, Universal DSL and VDSL.

ADSL (Asymmetrical Digital Subscriber Line) is designed primarily for the residential consumer market. The asymmetric means that the connection transmits data at faster speeds downstream from the Internet to your computer than upstream from your computer to the Internet. This is because DSL users rarely upload the same amounts of data as they download. ADSL can support speeds up to 8 megabits per second (mbps) downstream and up to 1 mbps upstream, although the connection rarely approaches those marks.

HDSL (High-Speed Digital Subscriber Line) offers equally fast upstream and downstream data-transmission speeds ranging from 784 kbps to 2 mbps.

IDSL (ISDN Digital Subscriber Line) also offers equally fast downstream and upstream speeds, but it's pegged at 144 kbps.

SDSL (Symmetrical Digital Subscriber Line) offers similar upstream and downstream speeds ranging from 385 kbps to 2 mbps.

Universal ADSL, which also is called "G.lite" service, is an easy-to-install DSL service primarily marketed for residential use. It supports downstream speeds of up to 1.5 mbps and upstream speeds of up to 512 kbps.

VDSL (Very High Bit-Rate Digital Subscriber Line) offers downstream speeds as high as 53 mbps and average upstream speeds of 2 mbps.

I sometimes see the term xDSL. What's that?
It's a generic term for all forms of DSL service spanning transmission speeds from 128 kbps to 52 mbps.

What are DSL's major advantages?   

Some advantages are:

• Speed.  It is fast.

• Availability.  It is always on. 

• Convenient.  It does not tie up your telephone line like dial-up service does.

• It does not interfere with caller ID, call waiting or other telephone features.

• It save time.

How fast is a DSL connection?
The technology can deliver data ranging from 128 kbps to 7.1 mbps. That IS six to 125 times faster than the standard dial-up connection speed of 28.8 or 56 kbps. A DSL broadband connection enables you to download huge files from the Internet in a fraction of the time it takes a dial-up service, move from web site to web site as if you were changing the channels on a TV set, access a growing range of news, entertainment and information resources, including specialized services being developed expressly to take advantage of broadband's blazing speeds.  You can do more in less time.

What does always on mean?
Once you've turned on your computer and clicked on your DSL connection to the Internet, you remain connected as long as your computer remains on.  There is no longer the need to dial a telephone number and then wait for your modem to connect you to the Internet every time you go online.  An always-on connection lets you hop on and off the world wide web whenever you want with no delay.  You can send an e-mail at a moments notice or access vast databases at the flip of a switch.

What are DSL's biggest drawbacks? 

Some Disadvantages to DSL are:

• It is available everywhere because of technological limitations. Copper lines can carry data using DSL's high frequencies only so far.  At some point the quality of the transmission erodes. 

• The speed that your DSL service provider boasts of for your connection can vary within a range and the access speeds that are quoted at maximum rates.  The same thing happens with modems and dial up accounts.  Variations in speeds are tied to the physical condition of the copper telephone line used for your DSL connection or the number of computers hooked up to your DSL link in your home or office.

Who offers DSL service?
Almost every telephone carrier in North America and Europe is at some stage of DSL deployment. That ranges from Bells such as Qwest and SBC Communications to independent companies such as GTE.   Click here for a list of providers.

How many DSL connections are there today?
Through the fall of 2001, DSL had been installed in over 1 million U.S. households. Some estimates are that 9 million users could have access by 2004.

How much does DSL service cost to install?
Prices vary and many companies offer free installation. Others charge $100 and up for a residential connection, and from $200 to $500 or more to connect a business.

How much will a DSL connection cost me per month?
Again, it varies. Your monthly bill will depend on your connection's speed and whether you've ordered extras like additional e-mail boxes. A typical home user can expect to pay $40 to $50 a month for service. Businesses can expect to pay from $150 to $300 a month.

What kind of equipment do I need?
Yes, a couple pieces of equipment are needed.  First, a DSL modem, commonly called a "router" is needed.  It is usually leased from your service provider and included in your monthly bill. Also, your computer also must connect to the router, which is done through an Ethernet cable that your DSL service vendor usually provides. Finally, to transform a telephone line into a high-speed data line, DSL equipment must be installed on both ends of the line (at the customer premises and the local telephone central office).

Can I buy my own router?
Yes. It will cost from $150 and $300. Before making a purchase, you should ask your DSL service provider to recommend a manufacturer or router model that will optimize the company's system with your computer.

Will the router run on my computer?
Probably. Most DSL companies require at least a Pentium processor and 40 megabytes of free space on your hard drive. If you purchased your computer within the last five years, you will probably meet those requirements.

How many DSL lines do I need?
You need one DSL connection for every Internet connection you want. With home networking more than one computer can share an Internet connection.

Can I use more than one computer on my DSL line?
Yes, but you will need unique High Speed Internet User IDs and passwords for each computer if they're used at the same time. Also, be aware that using more than one computer at a time can slow download speeds.

Should I worry about security issues with a DSL connection?
It depends on the level of trust you operate at in other areas of your life, your comfort level with technology and technology service providers, and the kinds of information you keep on your computer. Generally, it pays to take a few precautions the online equivalent of locking your front door to keep intruders at bay.

What precautions can I take?
If you have a Microsoft computer, turn off the file-sharing function. Get a good anti-virus program and have it scan your computer each week. Don't run a program or open an e-mail attachment without first running a virus scan.

Anything else I can do?
You might consider a firewall. It monitors your Internet connection and refuses to let anything suspicious into your computer. Software firewalls, like BlackICE Defender, are programs that you download from the Internet to your computer. These applications scan for hackers, just as anti-virus programs look for bugs that can disable your PC.