Completely baffled by network issue "Phone not allowed"

[Notuser]

I bought a S9 three days ago.
Everything worked fine until today. Today I got an error saying "unregistered sim card". I double checked with freedom that it was not black listed and that the device is unlocked. They gave me a new sim card but that didn't fix it. A bell sim card works, a virgin sim card works, and a Fido sim card works. What's going on? My sim card works in other devices. And other freedom sim cards don't work on mine.

 

[B. Diddy]

Welcome to Android Central! Did you try the Reset Network Settings option?

 

[Gayle Lynn]

You probably should have gotten some or many security updates or even 9.0 Pie.

Also the restore or transfer from another device. Which can mess up.

Not a bad idea to clear cache partition at this point as well as reset network.

Carrier, unlocked, source you bought from... ?

Changes you made in setting phone up, apps you added. All can play mischief.