BSNL Minimum Recharge Plan

Hey Guys, I am planning to port my Vodafone Number to BSNL. I use this number only for Incoming calls and for receiving OTP.
As you know Vodafone & Airtel charging min 49rs for 28 days outgoing validity. Also they providing 38 rs special talktime which is not useful.

I want to know which is the Best affordable plan for incoming validity in BSNL. I am from Tamilnadu Circle.

Dimers help needed. Thanks!