Phone Company Connections
As previously mentioned, your local phone company can offer DSL or dial-up Internet connections. Both of these connections are carried over the same lines as your phone calls throughout your house.
Dial-up connections use what's called a "circuit-switched" connection to your ISP -- that is, it remains connected constantly until you close the connection. This sounds like a good thing -- after all, traditional telephone service is circuit-switched -- but this also means that the line it uses can't receive any other connections while you're on the Internet, and every computer that needs a connection optimally should be given its own line. Though few ISPs actively promote dial-up packages for consumer use due to its slow speeds, they are still available and a good option if you need a low-speed, persistent connection, such as for a credit card line. The connection speed maximum as defined by the IEEE is 56 kilobits per second, or 56 Kbps.
A digital subscriber line, more commonly known as DSL, uses a "packet-switched" connection -- that is, your computer connects to the Internet through a DSL connection for long enough to send or receive information, then drops the connection to free it up for other computers to use. This process of acquiring and dropping the connection is transparent, since you don't have to do anything but surf the Internet for it to work. DSL is faster than dial-up, ranging from 128 Kbps to 8 megabits per second, or Mbps. DSL, like its predecessor dial-up, allows for a private connection, which means that the computers on your local network are the only ones that are on your connection all the way to the ISP. However, the connection speed can vary depending on the distance to your ISP. This connection type is best used in a private home or a small to medium business setting.