1. http://www.callingcards.com/ (10 minutes free)
2. http://www.mobilecaller.com/ (10 minutes free)
3. http://callingcard.com/ (10 minutes free)
You can try these 10 mins free calls, I am not sure if you will get 10+10+10=30 mins free calls because its operated by the same company, but You can try and let us know.
If you like the service you can also buy the calling card.
Enjoy free calls, do not forget to use free calls offers available on my website; you can search freevcalls, or explore the old blogs.
Now, I will not publish step by step instructions, if you have any problem for making free calls, you can leave a comment. I will try to help you.