I just discovered an app called mCent that gives free mobile airtime for trying apps on your phone. Give it a try. This app is on top for giving most rewards. Here is the link.
Https://MCent.com:443/app/?mcode=4AOGNI&tcx=OTHR
There is another app which is quite good in giving recharge.
Found an amazing app called Earn Talktime on Google Play with nearly 65 lakh users and 4.3 rating.
Earn unlimited free Talktime by simply downloading the app.
Click on http://8465982.earntalktime.com
Finally one more app which gives good compensation.
Http://ladooo.com/1472540066
Thanks
Ashish