Cannot Get Online Through Dial-up Modem


Hello. I have searched for an answer online but have not been able to find one. About a month ago, I tried to get online through my dial-up modem. I couldn't. When I tried to connect, I heard the dial tone plus a lot of fuzzy popping noises (almost like static). When the modem started dialing, it sounded really loud and distorted (like it was blasting out of the speaker even though my volume was low). I unchecked the box "Wait for dial tone" in the System Preferences and disconnected the phone line from the modem. Naturally, there was no dial tone when I tried to connect but when the modem dialed, it sounded normal. I plugged the line back in as it was dialing and suddenly heard it distorted again. It eventually got online after about five tries, but even then the connection speed was 10 kbps or lower (too slow to do anything really). The connection dropped off frequently as well.
A couple of days ago, the modem completely stopped functioning correctly. When I try to dial up, I hear the distorted dialing tones, but no dial tone itself. I know it is a working line because I tested it on a working telephone. Apparently, the modem is dialing without actually picking up the phone. I tested it by picking up "a" phone in the house as it was dialing and suddenly heard the dialtone kick in. It was very faint. So I tried dialing up with one of the phones off the hook. The modem dialed but I still heard a dial tone as if no one had dialed.

I consider myself to be a mostly experienced user but I have never seen anything like this before. Please help.

Thank you.
15" Powerbook G4 1.25 GHz
Mac OS 10.3.9