Probably for one of the four main reasons they exist. Steal money, get personal or financial information, hijack your computer, or see if your number's working. Going by previous posts, it looks like a live voice is required for what they're after, and besides, rarely will a random call from Indians be anything good. No kind of answer on your end, they're 0-for-4.
Your provider should be able to block the number. If it is your cell you probably can on that directly. Consider getting a landline phone that can block multiple numbers from it directly if your carrier can't help and you are going to keep the landline.
If you answer and have information about the call, you can report it to the FTC, FCC and your state AG. It takes forever for them to track down where the call is coming from and shut it down, so blocking is your best bet for relief.