For feature phone users/second sim users, the best choice is BSNL. In Rs.74 and 75 plan, they give 180 days validity. Around 12rs per 28 days. And their maximum tariff is 2p/s.
NB: Based on Kerala Circle. Check with your circle.
Could anyone please confirm if Rs 23 recharge is still valid for Airtel? It has been removed from Self-Care and Airtel App, but we can still do Rs 23 recharge from FreeCharge. Will it go thru or will it be rejected?