There are several methods of connecting to the internet like cable service, dial-up access, and DSL (Digital Subscriber Line). DSL is a high-speed connection that uses the same wires as a regular telephone line. Unlike dial-up access, DSL can be connected to the internet without interfering with your regular telephone service. This means you can surf and talk on your telephone at the same time, on the same phone line!

In order for this to work properly, a low-pass filter must be connected in-line to all of your telephones, fax machines, or dial-up modems you have connected to your phone lines. The low-pass filters separate voice frequencies from data frequencies. Simply put, these filters turn your phone line into a four-lane electronic highway. Two lanes are for sending and receiving voice and the other two are for sending and receiving data.

Even though DSL is an advanced technology there are still disadvantages. Not everyone can qualify for DSL service because DSL is a distance-sensitive technology. Only locations that are within 18,000 feet (3.4 miles) of the telephone company’s central office can receive the DSL signal. Even if you know where your central office is, looking at a map is no indication of the distance the DSL signal must travel between your location and the office. You might wonder why DSL signals have distance limitations but regular telephones don’t. The answer is a small amplifier called a loading coil that the telephone companies use to boost voice signals. Unfortunately, these loading coils will not let a DSL signal through, so a loading coil in the loop between your telephone and the telephone company's central office will disqualify you from receiving DSL service.

Since DSL is distance-sensitive, the farther away you are from the telephone company’s central office, the slower your speed is going to be. However, if you are switching from dial-up access to high speed DSL, even if you are far away from the central office, your speed will be around 16 times faster than your old dial-up connection.