I will be arriving in Kochi, and plan on purchasing a sim card at the airport. JIO has been the most recommended carrier so far. Any suggestions on a foreign national purchasing a sim card in India? I will be there 3 weeks.
BUYING - I travel to india for one month every year, and I just returned from this year's trip (Delhi & Assam). I saw something in the airport that was new to me - they were selling sims in vending machines at the gate in Newark. I was suspicious of this and did not buy one. When I arrived in India, my Indian friend assured me that you still had to provide proof of citizenship to purchase a sim. I spoke with my American contact there who confirmed that you need to have an Indian citizen purchase your sim for you. This is a simple thing since they can buy as many as they want, and you cannot throw a rock without hitting a sim shop. (I was told that U.S. citizens are issued a sim with an E-visa, but I have not confirmed that.)
JIO - I had never heard of Jio until this year. I purchased a Jio dongle and used my Indian friend's sim. As of August 2, I was still getting 2gb of data a day without paying anything. In years past I used airtel and aircel with which you had to purchase usage ahead of time by the gigabyte. The best thing to do is to take an unlocked smart phone and put a Jio sim into it because Jio devices you purchase there will be permanently locked to the Jio company that will surely be raising prices in the future.
Airtel - If you find that Jio is not an option for you, Airtel has a scheme that involves a one time enrollment fee that drops the price of data to near nothing. I used this scheme on my trip two years ago, and my friend told me that it is still available. You will probably need to ask for it though. 11 days ago