Modem disconnects often happen because of two possibilities. The phone line may be bad, or your modem may be defective.

If the phone line is bad, call the phone company and tell them you are hearing static on the line (You must indicate that you are actually hearing interference because your phone company will not support modem connections). They will try and fix the line, and then your problems may be resolved.

Modems occasionally deteriorate, sometimes even within a couple months after purchasing them. If you suspect your modem is defective and it is still under warranty, contact the modem manufacturer (or the PC manufacturer if it came with your system), and request a replacement.