I've got a strange problem with several USR Sportster 005686-03 modems that my company is using. Quite frequently we will notice that the CD light is on even though we are not dialed out. The only other light on at that time is CS.

So I run Hyperterminal to try and find out what is going on but the modem isn't procesing any commands that I send it. The RD light blinks when I enter my keystrokes so I know that the modem is at least receiving the commands. I've tried unplugging both the serial cable and the phone cable but neither of those actions will turn off the CD.

The only way I can get the modem back to a functional state is to toggle the power switch.

Ever since this started happening I've decided to watch the modem during our calls and I've noticed that the CD will stay on anywhere from 7 seconds to 30 minutes (I cycled the power at the time because I was tired of waiting) after the call has been disconnected (the TR goes off).

My init string does have &C1 (modem controls CD) and &D2 (DTE controls DTR) set. DIP switch #1 is up (DTR normal) and so is DIP switch #6 (Carrier Detect normal).

I have tried quite a few AT settings to try and correct this problem but I just can't seem to find the problem.

Has anyone seen this happen before with this modem?
Does anyone have any suggestions that I might try?