1)      Download  hotspot shield vpn and connect to it.

          Download VPN Here

2)      After connecting this vpn open below link
http://skype.hotspotshield.com/banner.php

 3)      After that click on free voucher code. That gives you voucher code .

4)      After completing that, login to your skype account . put that voucher code. And add credit in you account.

Note:  Must conncet with hotspot shield vpn. Otherwise this trick is not working.