There are Two Ways to get this 150mb on your mtn sim card, after you use the first way and exhaust the MB, use the second method and you will be rewarded with another 150mb and this will be making a total of 300 Awoof MB just for free.
Send GM in a text message to 2200
You will be awarded with 150MB
Check your MB balance by dialing *559#
Once you exhaust the mb use the method two to get another 150mb
Send JM in a text message to 2200
You will be awarded with another 150MB