Think of the telephone line at your home. That line—called a local loop—connects your telephone to the telephone company's local switch. When you make a call, the voice signal is carried over the line and switched to the central office to the party you are calling. Your connection is then complete. Because a dial-up connection uses the telephone line, it also uses this loop. The signal must be switched by the telephone company to the ISP service and go through a modem bank to complete your Internet connection. The result is a delayed connection to the Internet. To compensate for their phones lines being tied up, many people put in a second phone line just for the modem. However, modem connection speed is relatively slow—probably 56k at best—likely much slower.
DSL changes the way you connect. By attaching a DSL modem to your computer and using a Digital Subscriber Line Access Multiplexer (DSLAM) provided by the service provider (at the telephone company's switching office), your online activities bypass the local switch. This eliminates switching connections, the dial-up modem at your house, and the modem bank at the ISP, resulting in a much quicker connection speed. Because you aren't using the local switch, you're always connected to the Internet.
