Discontinue constant modem dial-tone

I am using the OApen FM56-ITU/2 modem on a Windows NT 4.0 PC. The telephone line is connected form the modem with a long cord to a wall jack on another side of the room. When I go to dial out, I can hear a voice message that says "you have exceeded the time for dialing." This seems to be due to the modem dial-tone constantly going even though the modem hasn't actually started dialing the number. After a short time, the computer prompts an error message that says, "Error 692: Hardware failure in port or attached device." Things I have done to avoid all of this so far include 1) unplugging the phone line from the phone jack and the opening the modem dial-out screen, then quickly running over to plug the phone line back into the jack, and running quickly back over to the computer and mouse clicking on the dial button; or 2) have someone stand at the phone jack, unplug the phone line, then I open the modem dial-out screen, tell the person to plug the phone line in the jack and they do, and then I mouse click on the dial button. Does anyone know of any better way to get this done? Is there some way to cut off the modem until I am ready to dial but still leave the phone line plugged into the phone jack?

Thanks.