call a number using skype in a webpage

This is the format for the link:

<a href="skype:echo123?call">Click</a> (make a call to echo123)

It will work provided the visitor have Skype installed.

You can find all the options and an alternative javascript to redirect the user to download skype is he/she does not have Skype installed.

http://dev.skype.com/skype-uri

Skype has a description of their URIs on their developer site:

http://dev.skype.com/skype-uri

How well these work is entirely up to your browser and OS.

<a href="skype:+CountryCodePhoneNumber?call">Click</a> 

(make a call to any PHONE NUMBER)

Please note that the Country Code is required. Without it call option will not show. If your database has numbers without country code, you can add the country code as +1 in your script. Skype will then give you the option to change country code before calling so you can change to required country if need be.