Error 680: There is no dial tone
This error is generally caused by a faulty modem, faulty modem cable, faulty phone line, corrupt Dial-Up Network (although the later is quite rare) or you are dialling on a non-standard phone line.
This error will appear if your computer's modem cannot detect a dial tone from your phone line. Firstly check that you phone line is working with a normal phone.
The modem is generally built-in to most computers although it can be an external device plugged into a modem port.The modem should have a phone line connecting into the phone line socket in the wall.
If this connection lead is faulty or too long (over 10 metres), it may not detect a dialtone properly.
Also, if you have other phone extensions in your home, make sure that none of the phones are off the hook. This would automatically make your phone line engaged and therefore your computer would not be able to dial onto the Internet.