Hi Bo, Firefox can't actually dial a phone number. It might be that an extension was installed that might have done something, and you can make sure it won't happen again by reseting Firefox and removing all extensions.

The Reset Firefox feature can fix many issues by restoring Firefox to its factory default state while saving your essential information. Note: This will cause you to lose any Extensions, Open websites, and some Preferences.

To Reset Firefox do the following:

1. Go to Firefox > Help > Troubleshooting Information.
2. Click the "Reset Firefox" button.
3. Firefox will close and reset. After Firefox is done, it will show a window with the information that is imported. Click Finish.
4. Firefox will open with all factory defaults applied.

Further information can be found in the Refresh Firefox - reset add-ons and settings article.

Did this fix your problems? Please report back to us!

Thank you.

Have you tried this - http://answers.microsoft.com/en-us/windows/forum/windows_7-networking/disable-to-opening-dial-up-connection-in-windows/1ea450ec-d9bb-45f4-bc89-25ca5ccfa3d7

Also, look at this - http://windows.microsoft.com/is-is/windows-vista/advanced-dial-up-settings# (scroll down to "To configure autodial" and click on it for details)

See also http://kb.mozillazine.org/Autoconnect