Call any Indian phone number -without spending money- with the great app Indycall. All you need to do is watch a couple brief ads to earn credits, and you'll be able to all your friends!
Indycall is very easy to use. Just dial the number you wish to call, or select a number from your contacts, and the call begins immediacy, so long as you have enough credits. If you don't have enough credits, and don't want to watch ads, you can easily buy a few with actual money.
On top of all that, you can also call internationally with this app, although it does cost more indyminutes (the app's currency). Overall, Indycall is a great communications app that you can use to make phone calls without spending a single cent.