Samsung Galaxy Luna is saying "invalid-SIM-card"!

[Serrune]

Why is it doing that, and how do i fix it? (Android 6.0.1, Android Security Patch level - July 1, 2K16)

 

[B. Diddy]

Welcome to Android Central! Does the SIM card work in other phones? You may need to ask your carrier for a replacement SIM card if it doesn't.