Apple this week provided troubleshooting steps for iPhone owners who are unable to activate iMessage with a phone number in iOS 26.

iOS 26 Messages Feature 2 1
According to Apple, some customers might not be able to activate iMessage with a phone number if there is an inactive SIM or eSIM with the same phone number as an active SIM on the ‌iPhone‌.

Customers who are experiencing this problem will see a “Not Delivered” alert for sent iMessages, and iMessages won’t be able to be received. Messages will be sent and received via