Error 680 means there is no dial tone. This either means the connection is waiting for a dial tone which there isnt going to be one, or that its using the wrong modem.

Basic Troubleshooting - Always complete these steps prior to Advanced Troubleshooting

1. Pull the battery out of the phone while it is disconnected from the computer and charger
2. Restart the computer
3. Verify the Phone is capable of browsing the internet on the phone
   Note If the phone is unable to browse itself, contact your wireless provider.
4. Verify the connection and settings are correct by following the Connection Setup again to check the settings
5. Test the connection again

Advanced Troubleshooting

Verify the Connection is using the right modem:

1. On the computer go to
   
   • Windows XP - Start > Control Panel > Network Connections
   • Windows Vista - Start > Control Panel > Network and Sharing Center > Manage Network Connections
   • Windows 7 - Start > Control Panel > Network and Sharing Center > Change Adapter Settings
     
2. Right click the Dial-up Connection then select Options
3. Verify under Connect using the only modem selected is the Phone (ie: Samsung Mobile USB Modem or LGE Mobile USB Modem)
4. Test the connection if a change is made.
   Note If the correct modem does not show up, verify the phone is connected and setup correctly.