Sim not valid on iPhone 6

[iMore Question]

My iPhone 6 update to 9.3.1 and my SIM card not work and sim not valid message popup on screen.

 

[Branta]

Eject the SIM and reinsert fully home. If that doesn't work try power off and reboot. If still no good try the. SIM in a different phone or a known good SIM in your phone. Finally contact your network and try a new SIM.