DSL Internet Services Explained

DSL stand for "Digital Subscriber Line" and is a technology for providing high speed Internet services to homes and small businesses over a standard tradtional phone line. It is known as an "always-on" service because unlike the old dial up service there is no logging on with user name and passwords required.

Setting up DSL service is easy. All you need to do is plug your PC into your modem (typically supplied by your service provider in most cases) and then from your modem to your normal telephone jack. This is illustrated in the diagram below.

DSL Internet service set-up

Types of DSL

Assymetric DSL (ADSL) service is the most common type used by homes and businesses. Assymetric means unequal and typically the transfer of information (data) from the Internet to your PC (download) is much faster than the transfer of information (data) from your PC to the Internet (upload). The assumption here is that most people acces information (download) rather than sending (uploading) information. Other variations are as follows:

Very high bit-rate Digital Subscriber Line (VDSL): As the name suggests this type of service provides higher Internet speed connections. The disadvantage is that it only works over shorter distances, (e.g. up to 4,500 feet or so).
Symmetric Digital Subscriber Line (SDSL): The name helps to give this one away also. It provides a symmetric connection (upload/download), meaning that the speed of receiving (download) and the speed of sending (upload) data is the same. With this type of service the user is unable to make phone calls at the same time as using the data connection. A small business may consider this option rather than a home user.
Rate-Adaptive Digital Subscriber Line (RADSL): A little more complicated, this version is similar to the more common assymetric service execpt that the modem has the ability to vary the connection speed based on the signal strength (meaning that it can adapt and provide higher speeds if there is a "good" connection, and adapt to more robust signalling and lower speeds for longer and lower quality connections).

Speed

Available speeds from this type of service are continually improving. It use to be that the only option was a 1.0Mbps downlink and a 128kbps uplink plan. As technology has improved enhanced plans are being offered claiming speeds up to 15Mbps (and more depending on your location) on the downlink and 384kbps on the uplink. Of course, you pay a premium for the enhanced service options but this technology still remains one of the cheaper options for Internet access in your home and small business. It may not always be the cheapest option as typically service providers require you to also subscribe to their phone service, which can be costly compared with an option like VoIP.

Your speed will depend on the distance that you are from the telephone company Central Office (CO). Typically, the closer you are the faster your Internet speed will be. There is a maximum working distance of 18,000 feet, as illustrated in the diagram below.

DSL Service infrastructure

So, for you to get service you will need to make sure you are within this limit from your local telephone (provider) company central office. This is easy to do. You just go to the service provider website that you are interested in, enter your telephone number details and the search will check to see if it is available to you.

Pricing

As mentioned previously, this technology provides one of the cheapest options for getting Internet service to your home and small business. Many providers start their standard plans in the $20 per month range and this typically gets you the 1Mbps range download speed. Expect to pay in the $35 to $40 per month range for enhanced plans with increased speeds.

Advantages and Disadvantages

Here are some advantages to consider:

It is "always-on" and you can still use the phone line for voice calls.
Typical speeds are much faster than dial-up service.
You can use the phone line you already have at your home or business.
The modem is typically supplied to you by the service provider at no cost.
Fixed monthly billing, regardless of usage time.
You may be able to take advantage of VoIP phone service if the provider doe snot require you to subscribe to their phone solution. For more information take a look at our VoIP section.

Here are some disadvantages to consider:

Speed depends on the distance between you and the phone companies Central Office used.
It is not symmetrical in that the uplink speed is slower than the downlink speed.
Service is not available everywhere.
Service requires a local telephone line connection.

Summary

Overall, DSL Internet service is an excellent choice for high speed broadband access. Check out our DSL vs Cable guide for a comparison summary between the two main broadband technologies available.