I searched regarding data SIM in India but seems the information available are a bit out dated.

I will be arriving DEL terminal 3 (international) around 4am on a Tuesday. I'm wondering if the Airtel booth in the arrival lobby is open 24 hours? If not open, is there another place I could get a SIM card in the city that knows about the foreigner activation process? In particular I need 3G data access.

I am not an Indian citizen and am on a tourist VISA. I wonder if someone has experience getting a SIM card recently.