My problem is the same as bamabud's, quoted below -- however, the 1998-vintage solutions suggested to him won't work for me, since it is happening to two iMacs (tray-loading) I have, one running OS 9.2, the other OS 10.3.
What's odd is that it was only happening on the OS 9 iMac at first. Then I tried connecting that iMac's modem to the phone line I had the OS X iMac on, since I knew it worked fine. The OS 9 iMac's problem persisted -- and then, when I re-connected OS X iMac to that line, the same problem started with its modem. It was as if the sick iMac's modem had left a virus on the phone jack that transmitted it to the healthy one!
I've tried switching scripts to v.32 and to Hayes, but that has no effect. (I connect to the Internet through AOL, if that is relevant.) I have switched out every possible phone line and connection, to no effect, and tried switching the modem off through Network preferences -- nothing. I'm writing this from a library computer, and am desperate for a solution!
Here's the quote from elsewhere on experts-exchange:
Modem won't disconnect
asked by bamabud on 05/05/1998 06:38AM PDT
This solution was worth 50 Points and received a grade of C
I have a Performa 6320CD with an internal modem (teleport silver?) and when the modem is plugged into the phone jack, it opens the telephone line and won't disconnect causing the "european siren" and "please hang up and try your call again" along with static and silence. Regular telephone works and will disconnect when the call is completed, but the modem won't disconnect. I have to unplug the modem line from the phone jack, plug it back into the wall and immediately sign on to the application using the modem to get an outside line.
This problem just began two nights ago after having the computer almost two years. I have installed no new software.