Doubtful you'll have luck with any of that as you're likely dealing with an overseas caller. The times they called you would be 12 hours ahead and we'll within business hours in India. It's quite possible it's a computer calling as well, looking for numbers that either have an automatic answer, or live voice taking the calls. Since you're likely unable to be without a phone for overnight hours, consider a call blocker. If you could do it, which it's doubtful you can miss possible emergencies, you could try disconnecting the line, or turning off the ringer during the night hours. Calls like that at unreasonable hours are usually looking for who's answering their phones then.
Harassment at its best, Over 500 calls over a period of one month and it does not stop ! These clowns will be reported to FTC for electronic communications harassment !