How do I turn off the Telephone number formatting in the browser window.
You have to deactivate or uninstall the Skype Add-on.
In newer versions there is also the option to just turn the highlighting off in the settings of the Add-on.
Here is a link to the Skype FAQ:
Just incase any developers out there are wondering who to stop this form mucking up there pages, or design, you could try and insert some hidden code, for example:
01234 <span style="display:none;">_</span> 123123