I hear noise or hissing on my telephone line. Modem connections are very sensitive to "line noise," or problems with phone line quality. This can be caused by old or poor wiring inside your home, or conditions affecting the line between your home and the number you are dialing.
Make sure that you have installed a telephone cord between a working phone jack and your analog modem, and that all connections are secure. Most times, analog modems are installed inside computers, with a phone jack in the back of the computer.
If you have problems with phone line quality, contact your local telephone company.