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Are you using an alternative sim card that's activated @7575jone
i.e it connects to mobile data.
Also some Samsung phones need a mastercode as well as the Nuc.
Customer service can help with that and or give you the Nuc email address and Samsung customer services maybe able to help you with this but can't help with actual unlocking.
Current Phone > Samsung Note 9 _512Gb > Model: SM-N960 Hybrid-Duos.
Samsung One Ui / Pie.
Samsung Gear s3 Frontier Watch.