Recharge 2rs and get 500mb 3g net on airtel.
And there is this Special offer running on Whatsapp too
http://*R...ed* Hey Friends, PayTm is offering 1 Year of Unlimited 3G Recharge as Promotional Offer! Do not pay for 3G in 2016. Get Unlimited 3G Data for 1 year for free! NOTE: Offer Valid only till Tomorrow!