My Name is Baron Wisdom, its better you ensure that you have done the NIN registration before linking your Sim card to avoid complications when you misplace your Sim card.
Also Read: NIMC MOBILE APP STEP BY STEP WAYS TO LINK YOUR PHONE NUMBER
I saw some post indicating that once you have done your BVN before that you have automatically registered your NIN registration also.
Please its important you take note that most of the Sim card we are using today are resold by the network providers.
Once a Sim card is inactive for a year, they disconnect, reproduce and sell it off to another customer in Nigeria. The real and first owners of those sim might have enrolled in the NIN before they either died, got rubbed or lost their sim card while others got discouraged retrieving it after seeing the stress it will take them they prefer going for a new sim just like some persons do receive strange call, sms and bank alert.
My humble submission if you must link up your sim when your not too sure of the NIN your sim pulled out for you.
Kindly visit your google play store to download the NIMC mobile app which you will have to input your NIN and your details will show before you proceed in linking your Sim.
My Name is Baron Wisdom, CEO Baron Information Technology