Error 680 or no dial tone when you try connecting to internet

When you try connecting to the internet using your mobile broadband device, do you see error 680 or an error that there is no dial tone?

Then, the below post may help you to identify the issue and get the connection working

This may happen if you have more than one modem configured on the computer. Some computers come with a in built modem and after plugging in the mobile broadband device, there might be two modems. And the connection manager might configure a dial-up connection which uses the wrong modem. So the connection might actually be trying to use the in-built modem when you want it use the device.

How to verify if this is the issue?

You will need to verify if the dial-up connection that your ISV’s connection manager creates is using the wrong modem. Steps to track this are below:

  • netsh ras set tracing * disable
  • del %windir%\tracing\*.*
  • netsh ras set tracing * enable
  • Dial your connection using the connection manager/dialer application
  • netsh ras set tracing * disable
  • Open %windir%\tracing\RASMAN.log and search for "ProtocolStart: EntryName:”. Note the entry name here.
  • Open the network connections folder. Start –> Control Panel –> Network and Sharing Center –> Click on ‘Change adapter settings’ in the left pane.
  • You will see the connection whose name was present in the log file here.
  • Rightclick on the connection –> Properties –> Go to the ‘General’ tab
  • Check if the modem selected here is the correct one. If not correct it.


  • Dial this connection from here –> Rightclick –> Connect and verify that it connects

[This posting is provided "AS IS" with no warranties, and confers no rights.]


Janani Vasudevan [*]

Windows Enterprise Networking

* Remove the online to mail me

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