few thoughts about
iPhone and its data capabilites on cellular network in India:
I have been using iPhone on Airtel since Jan(iPhone 1st Gen though).
even while you are in an area which has EDGE coverege, Internet Browsing sucks. lets not talk about areas which doesn't have EDGE as with GPRS it would be as good(should I say bad?) as dialup internet access. with hopes of 3G network launch in India in near future fading away(as Counsil of ministers are supposed to look into spectrum and policy issues and current UPA govt's future is uncertain) iPhone would not make any sense with respect to data access via Cellular network.
So, what ever the data plan Airtel/Vodafone offers, it can't provide a good browsing speeds while you are on the move.
I never used EDGE/GPRS for more than a week continuously. I always subscribe for weekly plans in Airtel when I am on move.
how much time it takes to reach 500 MB/1GB limits using a EDGE/GPRS connection in iPhone? Also think about the fact that you can't connect your iPhone to
laptop/desktop for browsing internet from laptop using iPhone EDGE/GPRS capability. you can't use iPhone as a modem.
Second thing is: using iPhone how much browsing you will be doing per month. you can't download any files using safari in iPhone. only thing you can do using iPhone's internet capability is: Browsing, e-mails and You Tube.
I don't think anyone would attempt to view youtube videos over EDGE/GPRS connection.
So, in the options rachit_1804 guessed, 499 - 500 MB free & 5p/10KB would be best one.
Currently Airtel offers(at least in Bangalore) a Weekly unlimited data plan for Rs.140/- per week. So per month it would cost Rs.560/- and it is unlimited.
I don't think Airtel/Vodafone would be launching new data plans for iPhone.
So, if you are thinking that with iPhone all you internet access problems on the go are solved, please think again. using iPhone 3G in India currently is equivalent to using iPhone 1'st gen in India.
But, I like the iPhone for its other features.