How does iPhone X work without a SIM card?
I am changing our providers on phones and there was NO SIM card in my husband's phone. what does that mean
[Re-Titled by Moderator]
Are you sure it is an iPhone X? Go to Settings > General > About > Model Name.
An iPhone XS and later can use an e-SIM instead of a physical SIM. See: About eSIM on iPhone - Apple Support