I did welcome back, I can’t make calls because it says you have been barred from this service

I want to know why I can’t make calls with my sim I just did welcome back today and it has lasted for 3hours

I tried making a call recently and was met with a "Your line has been barred because you have no service".

I cant call out and I can't browse with my mtn line since yesterday. Its saying my line is barred I dont have services. Pls kindly help me to resolve this. It's my business line