Lately my brother received an impromptu message from mtn which am sure most mtn subscribers also received that; he should re-register his Sim as inability todo so might leads to deactivation of his Line.
Without beating around the bush, he did the registration and was told the sim will be okay after some specific time. After the time given, he checked his sim but the result was still the same as before he did the reg ("Insert SIM Card" on his phone. He went back two times and was told that nothing is wrong with the sim from their side since he had did the necessary registration.
After coming back home the 3rd time, he insert his sim card into my phone and the sim works! I dialed a number, check account balance and everything was okay. Now back to his phone, the sim went back to his "Not Working Mode". After testing with different device, it was deduce that the sim works on some phone but not working on some. "WHAT KINDA OF SIM IS THAT? I thought to myself

NOW my brother don buy another small phone so e fit dey use am but the sim still no gree work for the phone, wetin fit cause this. My brother and Sister wey sabi, abeg your suggestion and idea.

Try putting another sim in that fone. Maybe the problem was with the fone

Wait Lemme consult amadiora

The sim has been infected by a virus called modullla spiral Lee virus...

It's a real sim virus and it can be dealt with tho

Tuham:
Lately my brother received an impromptu message from mtn which am sure most mtn subscribers also received that; he should re-register his Sim as inability todo so might leads to deactivation of his Line.
Without beating around the bush, he did the registration and was told the sim will be okay after some specific time. After the time given, he checked his sim but the result was still the same as before he did the reg ("Insert SIM Card" on his phone. He went back two times and was told that nothing is wrong with the sim from their side since he had did the necessary registration.
After coming back home the 3rd time, he insert his sim card into my phone and the sim works! I dialed a number, check account balance and everything was okay. Now back to his phone, the sim went back to his "Not Working Mode". After testing with different device, it was deduce that the sim works on some phone but not working on some. "WHAT KINDA OF SIM IS THAT? I thought to myself

NOW my brother don buy another small phone so e fit dey use am but the sim still no gree work for the phone, wetin fit cause this. My brother and Sister wey sabi, abeg your suggestion and idea.

Do a welcome back

ladyF:
Try putting another sim in that fone. Maybe the problem was with the fone

My brother did that and the Sim works in some phones and doesn't work on some.
Kinda of selecting phone

Swaggzkid:
Wait Lemme consult amadiora

Waiting... don't just be long

Melahou:
The sim has been infected by a virus called modullla spiral Lee virus...

It's a real sim virus and it can be dealt with tho

What! For real?

gbenga4my:

Do a welcome back

He already went for that and they told him since the sim is working fine, he needn't not to do so.
Maybe he'll have to go back and insist.

Tuham:

He already went for that and they told him since the sim is working fine, he needn't not to do so.
Maybe he'll have to go back and insist.

Don't mind those customer care representative dey knw ntn. Welcome bck is the best bet for such case

Use erasEr to clean the sim micro chip and insert again

gbenga4my:

Don't mind those customer care representative dey knw ntn. Welcome bck is the best bet for such case

Thanks bro. I think thats the best option

Tuham:

Thanks bro. I think thats the best option

Don't tell them you have a working SIM.
Tell them your phone was stolen

.....! @O.P, I also have same issue. The best bet is to do the welcome back /Sim swap!.....