Overview

• Apple’s support guidance says iMessage may not activate with a phone number if an inactive SIM or eSIM shares the same number as the active line.
• Affected users report “Not Delivered” notices, green-bubble SMS or RCS fallback, messages sending from an email address, or the number appearing twice in Send & Receive.
• The prescribed remedy is to remove the inactive SIM in Settings > Cellular (eject a physical SIM or delete the inactive eSIM) and then re-enable the number in Settings > Messages > Send & Receive.
• Users have encountered the issue since updating to iOS 26, with reports more common on devices that switched carriers, changed SIM setups, or migrated from a physical SIM to eSIM without deleting the old entry.
• Tech outlets corroborated the steps and note that iMessage typically resumes promptly after the change, though some devices may take a few minutes to update.