Solution:

1. Do you hear a dial tone through your modem's speaker when you click on 'Dial'? If not, verify that your modem is connected properly to the wall jack.
2. Do you hear ringing only? If so, verify that you have entered the phone number in correctly. If you're on campus, make sure you're dialing 9 before the number.
3. Do you hear negotiation starting and then terminating after a short time? If so, check the "Cancel this call if not connected within" specified in the connection tab in the Connectoid properties. Set the timeout period to at least 60, or even 90 if you have a poor phone line.
4. If the above does not work, try disabling V90 or forcing the modem to use V34 protocol, try disabling compression, or check for newer firmware releases or drivers for your modem.