I think this is a great ask, a few weeks back a Wikimedian doing a research was in Ghana doing some research and we had an opportunity to test Wikipedia zero on our MTN both times there was a bit of deduction but very minimal.  He asked me to do further research into what we where suspecting. But from then till date I haven't had the time to do that. Maybe we can write to MTN through the User group if they can help with that. Would be great though. 

Best.

Justice.