Originally Posted by GUWonder

Is proof of residency now required for purchase/activation of a SIM card?

In practice, what's been previously required (generally) is at least a photo copy of the passport "face page" or some other ID documents, whether a resident of India or not.

Worst case, most any party retained while in India -- say a licensed driver -- would be more than willing to get a prepaid account activated in their name for the use of their client.