> You can get a local prepaid phone number sim at the airport.

Worth noting, do all this before you leave the airport. Assuming you land in Delhi, once you leave the airport there's no way to get back in unless you have flight information to show

This turned into a pretty big problem for me on my first trip to India once I exited the airport with no way to make phone calls, no data, no sense of where anything was, and no rupees (I hadn't exchanged cash yet)