On those Windows machines with Skype installed, it tends to convert all phone-formatted numbers to Skype links so you can click it in order to make a call on Skype.
EDIT: Sorry, I just discovered that IE9 has issues with this solution as it does not support soft hyphens.
There is an alternative solution to this problem:
You can use a soft-hyphen character (
) inside the phone number to address the issue. For example, given the number
0664 111 222 3
change to
0664 111 222 3
and be happy :)