Recently, MTN Nigeria implemented Do Not Disturb (DND) policy which has the effect of stopping bulk SMS and other third party SMS from reaching MTN subscribers. This policy affects about half the subscriber phone numbers on MTN as MTN appears to have activated the DND service on many lines automatically even without the owners consent.
Due to this unforeseen event, sending bulk SMS to persons who previously received our SMS now has a reduced rate of delivery.
As a bulk SMS user if you notice that some numbers that used to receive bulk SMS service are no longer delivering, what you need to do contact all your members using the regular SMS on your phone just once.
You will have to inform them to send ALLOW to 2442 to disable the DND service.
To check if your line is being limited by DND, use the following:
Once the above is done, you will get a feedback telling you if you are active on it or not. If you are,
If unblocking does not work, then you can do it online via https://www.donotdisturb.mtnonline.com:8081/vasportal
You can read more about this directly from MTN Nigeria here.