Airtel free mb trial is still working, despite the fact that it has been available for over 2 years and, sincerely that was the first cheat i ever tried and knew all my life not until i met Google. OMG! "Those days".
Let's cut the long story short, the Airtel free mb trial still exist and it's working on selected sims.
So, don't get dissappionted when it doesn't work for you, just keeping dialing and am sure you will get yours' activated in no time.
Airtel Free mb trial codes
=>For 200mb; dial *141*13*200#
=>For 100mb; dial *141*13*100#
=>For 50mb; dial *141*13*50#
=>For 5mb; dial *948#
=>For 1mb; dial *141*13*1#
Ya men! What are you waiting for? Keep dialing, and you might see this;