A whatsapp user shared this, this morning plus i tried it and it works well.
He wrote: "Finally, MTN listened after so much had been FINED on them by NCC.
To opt out of all MTN useless adverts, dial *123*5*4# and follow the instructions.
No more 32043, 33070, 5010, 4100, etc. Especially Isa49v........ Only Bank Credit Alerts.
Save a life today by sharing.
It is real because i just opted out of MTN mobile advertising bullshit!."
Enjoy: drop your testimonies..