Since iOS 26 was released last month, some iPhone users have had problems using iMessage with their phone numbers. Apple has now published a new support document on its website addressing the problem and providing a potential fix.
Here’s how Apple describes the problem:
When you update to iOS 26, you might not be able to activate iMessage with your phone number if you have an inactive SIM with the same phone number as your active SIM.
Read more at 9to5Mac.com