Error 680 - No Dialtone.
  1. Check cable is correctly inserted into back of modem and phone socket.
  2. Check properties of connection, make sure correct modem is being used.
  3. Disable "wait for dialtone before dialing" in My Computer > Dial Up Networking > Properties of Connectoid > Configure > Connection > remove checkmark under call preferences.
  4. Too many devices on the line, try removing Fax Machines or anything else connected to the line.
  5. Make sure no one is using the Telephone when trying to connect.