Primary SIM card not recognized after upgrading to iOS 26

Question

Level 1

4 points

Primary SIM card not recognized after upgrading to iOS 26

Device: iPhone 16 Pro Max

Issue: After upgrading from iOS 18.5 to iOS 26, the primary SIM card is no longer recognized while the secondary SIM functions normally, resulting in loss of voice, messaging, and data services.

Impact: Communication functions are severely affected, significantly degrading the user experience.

Expected Result: Requesting the engineering team to resolve this compatibility issue in future firmware updates to provide a better user experience.

Note: The device was originally purchased in the United States. After returning to Mainland China, due to lack of eSIM support, it was modified via third-party channels to support dual physical SIMs for usability.

iPhone 16 Pro Max

Posted on Sep 20, 2025 10:07 AM

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Answer 1

kb1951

Level 10

126,347 points

Sep 20, 2025 10:41 AM in response to WoaiCBi

I would not expect Apple to make any modifications to the software. You purchased a phone in a different country from where you are using it. You had it modified by a non-Apple business which resulted in this problem. About all you can do is go back there to see if they can correct the problem.

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Answer 2

WheelieNick

Level 8

46,625 points

Sep 20, 2025 10:21 AM in response to WoaiCBi

I guess the modifying is the culprit.. that is not supported and that can cause issues

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Answer 3

WoaiCBi Author

Level 1

4 points

Sep 20, 2025 10:49 AM in response to kb1951

The issue with the primary SIM not being recognized arises from substantial underlying system changes introduced in iOS 26.

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Answer 4

kb1951

Level 10

126,347 points

Sep 20, 2025 11:13 AM in response to WoaiCBi

You can send feedback to Apple here regarding your experience: Product Feedback - Apple

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Answer 5

WoaiCBi Author

Level 1

4 points

Sep 20, 2025 10:25 AM in response to WheelieNick

I understand that third-party modifications are not officially supported, but my concern is that after upgrading to iOS 26, the primary SIM is no longer recognized, which severely impacts the device’s usability in Mainland China. I hope the engineering team can address this compatibility issue through a firmware or baseband update, as the device remains an official Apple product even though it has been modified to support dual physical SIMs.

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Primary SIM card not recognized after upgrading to iOS 26

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