If you are having problems staying connected, your phone line may be a big part of the problem. When talking to people on the phone, take a moment and notice if there is any interference, noise, static, etc., in the background. The more interference on the phone line, the harder it is for your modem to connect at a fast speed and stay connected to the Internet. If your modem is frequently disconnected while you're on the Internet or you get slow connect speeds, it's most likely because there is interference on the line and your modem cannot deal with it. Noise on the phone lines (caused by many sources) is often the culprit.

Note the weather. Many times the phone lines will not work well with data when weather conditions are bad. Phone lines were not made for the transmission of data.

Another thing to take into consideration is the quality of the phone line going from the wall to your computer. Old wires, or wires that are put under a lot of stress aren't very reliable.