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.
Try this. It substitutes spaces in the phone number with an invisible span + the original space char. So skype cannot understand it is a number and our beloved phone number stays the same :) I had to use this approach since I usually let the content administrator change phone numbers at his will therefore I could not use a hard coded number inside javascript. Of course your markup should look like your number with some spaces inside it.
$(document).ready(function() {
if ($(".phone_number").length>0) {
$(".phone_number").each(function() {
$(this).html($(this).html().replace(/\s/g," "));
});
}
});