The MTN MCN is a service by MTN that gives you notifications of calls missed while your phone was out of coverage or switched
off. Just like Etisalat's missed call notification for easy
starter subscribers.

With the MTN MCN or
Missed Call Notification,
you will always be inform by text of
any number which tried to call you when your phone is switched off or
out of coverage. The service is free and it's
available to all MTN subscribers. You will get the SMS from
MTN once your phone is available and the caller will also be alerted. The text message will be sent
to you in the person's no and it will also contain the callers phone no.

How To Activate The Free MTN Misses Call
Notification (MCN)

To subscribe, just text
" MCN" to 131.
You should get a text
message saying:
"Y’ello! You have
successfully subscribed
to Missed Call Alert for free. You will now
receive notifications
for all calls missed. 
To opt-out, text NOMCN to 131".

The service is free and it's available to all subscribers.
How To Deactivate The Service To deactivate, just text
" NOMCN" to 131 and the service will be deactivated