i, unfortunately, didn’t pick up a SIM card at Delhi airport because i thought the hotel ride was waiting outside, and when i discovered he wasn’t (and needed to call), discovered you can’t reenter the arrivals hall! i had heard that Indian SIM cards require several hours to activate — which i found to be true — but remember seeing a sign on at least one of the cell phone provider booths that they had instant activation. oh well.
luckily, there was a Vodafone store near my hotel in Connaught Place. note that many stores in India do not open until later in the day; this one didn’t open until 10:30.
getting the SIM card was not difficult, but you will need a passport photo (thanks prepaidwithdata wiki for the heads up) and address of your hotel. they will make a photocopy of your passport and you’ll need to sign in several places on a form. be sure to ask for the right SIM card size; they had nano-SIMs available.
the 1GB plan i bought was 255 rupees and the SIM card i believe was somewhere around 100 rs, or a total cost of about $5.75. (SO CHEAP)
there are several steps to activating the card. i was told it would take up to four hours for the card itself to join the network — in my case it was around three. once it switches from “No Signal” to having service and you get the first welcome message (the 1:18 PM one), you need to call 117 to verify your address with an agent to activate service. the representative at the store wrote down for me exactly the address she put on the form so i was able to just read it off. there is service in English (as with most things in India). you will get a second text message (1:37) once the card is fully up.
unfortunately, the representative at the store did not set up the data plan i bought so i had to return to the store. she loaded my money (3:16 message) and set up the data plan, which took about 20 minutes to activate (the 3:38 message).
service waffled between 3G and EDGE, but turning Airplane Mode on and off usually get me back on 3G. data speeds on EDGE were very slow (almost unusable); 3G was quite speedy — faster than hotel wifi at times, even. the SIM card is LTE-enabled, but i never got LTE service.
i saw a sign in the store that said there was free data roaming across India (which i verified with the representative) but i texted “roaming” to 111 like i saw on the sign just in case, but i think the reply was purely informational — the roaming capability is already enabled by default.
i turned on Data Roaming in my phone’s Settings (Settings –> Cellular) and my phone was able to automatically roam on the Airtel network (which got service in some places where Vodafone was weak). i didn’t seem to get charged any penalties for this, so changing that setting could only help. note that iMessage was unable to activate, i guess because i was unable to receive international texts.
you can check your data usage by dialing *111#, then choosing option 6 and then option 2 (menu options may change; just follow the prompts).
you’ll get these roaming text messages as you travel from state to state; they’re safe to ignore but a cool way to watch your progress around the country.