The skype API (found here http://developer.skype.com/skype-uris) allows you to use links on a webpage to initiate calls.
From the documentation.
In its simplest form, you can embed a hyperlink referencing a Skype URI in a webpage to place a Skype call. For example, to initiate a call to the Skype Echo / Sound Test Service, the link would be:
<a href="skype:echo123?call">Call the Skype Echo / Sound Test Service</a>
In the example above this will call the echo123 contact. There are many more ways of handeling this request. I suggest reading the documentation above as it provides methods of directly calling numbers.
Hope this helps.