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.

FIX:

Test modem by dialling a number through HyperTerminal or phone dialler. This will test the Modem without using Dialup Networking.

Make sure you are using the correct and/or original cable. Some modems used specific wiring which is not compatible with standard modem cables.

Check that you phone line is working with a normal phone.

Make sure the phone line you are trying to dial on is not a non-standard line, this can cause problems also.

If all the above are OK then get a new modem or test in a different location. Modems are very inexpensive now.