Network Locked SIM card on Unlocked Note 9 Have a Note9 on Tesco mobile, they have confirmned it is unlocked. I can use other UK SIM cards in this.

Trying my AIS (Thailand) SIM it asks me for a PIN for the Network Unlock?

Could this be a ROM issue? Is the phone region locked?

Any suggestions?

Cheers
OK Digging around found the solution.

Samsung devices have a regional warranty lock, I needed to make a 5-10 minute call to a local number using the Tesco SIM to unlock the phone for use with networks outside that region.

It is clearly printed on the box, but Tesco helpfully put thier own welcom to Tesco mnobile sticker over this.