There were a lot of people huddling around the Airtel stall at T3 when l was there a few weeks ago, but they all looked very stressed so cannot say if they were sold one or not.

ln the end l bought a Simcard from the UK which included free roaming in lndia. lt was only GBP 6 so not much more than Airtel charge at the airport and avoided all the stress and queueing.