This is known as "MTN STAFF OFFER"
The idea is that mtn official staff are given #20,000bonus 200sms and 500mb evry three three months. i.e they will continuously be receiving this offer every three three months.

I attend a seminar, where I met one runs guy MTN official Staff who tut me a trick to become MTN STAFF and be receiving #20,000bonus 200sms and 500mb every three three months, he also tut me how to make the 500mb 3gig
He made me to understand dat each MTN official staff has personal STAFF IDENTITY CODE [S.I.D.] this code is used to activate the offer.
So he generated 50 unused staff code for me and give me his number to get more when am tru with the 50 he gave me.
This has been tested in more than eight sim and is working fine.
But two sim or two people can’t use the same code.
To Get This Offer Follow The Following Steps:
Step 1: buy new MTN sim .
Step 2: go for registration, and during the registration, choose TELECOMUNICATION as your occupation.
Step 3: pm or call me on 08185384977 or 0812367419 to get your staff code
Step 4: Text the staff code I will send to you to 131, u will receive a message that YOUR STAFF OFFER PLAN HAS BEEN ACTIVATED,
YOU HAVE CREDITED WITH 20000 bonus; 200 sms; 500mb.

NOTE: You will continiously be given dis offer every three three months