Here is a trick to make free calls from skype on computer to any mobile number.

First of all, u will need 2 skype accounts and skype application in your computer and mobile. With one a/c 'sing in' in skype in computer. Then with 2nd a/c 'sign in ' in mobile's skype application. Then add your 2nd a/c as a contact in your 1st a/c and add the number you want to call in contact detail. Then add this contact. In your 1st a/c your 2nd a/c will appear online. Then click on that contact and make video call. Don't make mobile call. On making video call you will be connected to the number you entered in the contact. That's how you can make free call.

When u want to make call to another number. Just delete that contact and add that same contact with other number.
That's all.