This is one of the *144# offers introduced by Airtel. If your SIM works with *144#, you have higher chance of getting this offer. Dial *144*97# and you will be given 300mb for N700 and it will last for 30 days.
Not all SIMs are eligible. Dial the code first before buying recharge card. If you receive a response that ''You have insufficient balance", that means you are eligible for the offer. You can go ahead and recharge. But if the response is " GET 1.5GB FOR N1,000'', this means you are not eligible, i.e, don't recharge