Iphone6
iPhone 6, iOS 12
User profile for user:
i_rina
User level:
Community Specialist
Hello, ashik261!
Thanks for reaching out to the Apple Support Communities! It sounds like you are seeing an error that the SIM is not valid on your device. Based on the message on the device, if you're trying to unlock the iPhone for use with another carrier, check out this article for How to unlock your iPhone for use with a different carrier. This article will give you the steps you'll need to take to unlock the device for use with another carrier.
If that's not the case, check out this article If you see 'invalid SIM' or 'no SIM' on your iPhone or iPad. This article will give you the steps you can take for issues with the SIM card in your iPhone, as well as the next steps to take if you continue to have issues.
Cheers!