Depends on the browser
but it may be something like:

* Open your browser and look for the blue Skype icon in the upper right-hand corner (icon should be blue with an "S" and "123" with a green phone image)

* Click on the Skype icon.

* A window will pop up asking you if want to "Turn number highlighting on". Uncheck the box to disable and click "OK".

* Now open up a site that you know had clickable numbers on it and test to see if it worked
( magnum, Wed 24 Jun 2009, 19:43, archived)

u fucker
!!
( awallafashagba Da da da da da Dah dah, Wed 24 Jun 2009, 19:46, archived)

Doesn't it install itself as an add on?
Think I just removed it.
( broadsword, Wed 24 Jun 2009, 20:06, archived)