How to receive verification code for SIM card on iPhone?

• The Phone number isn’t set as a trusted Phone Number in your Apple ID
• Your carrier is blocking/lagging SMS delivery. SMS is not provided by Apple Inc
• You recently switched SIMs/eSIM, and Apple hasn’t refreshed the trusted number

Try “Get code another way. On the verification screen, tap:

Didn’t get a verification code?

Then choose:

• Send via Text
• Call this number
• Use another trusted device

The phone number assigned to your SIM may be registered to a different Apple Account. If applicable, this will prevent forwarding of incoming messages to the Messages App on your iPhone; you may need to temporarily deregister your phone number:

Deregister iMessage on your iPhone or online - Apple Support