Direct answer
A wrong result requires checking inputs, mode, calibration and output separately; a working control path can still be configured for the wrong state. For iPhone eSIM or cellular line, first check Settings for the line status and test the carrier QR/app on stable Wi-Fi.
What this covers
- iPhone eSIM or cellular line with this exact failure state
- Diagnosis across carrier provisioning versus device lock, line selection and activation network
- Customer-accessible observation, settings and external components
What it does not cover
- ×A displayed manufacturer error code with a different documented meaning
- ×Live electrical, sealed-system, internal battery-cell or gas repair
- ×A claim that every model exposes identical controls
Capture the exact failure state
ReversibleWrite down the selected mode, input conditions and the exact unexpected output. Expected behavior: activate the intended carrier plan and remain selected for calls, texts and data.
Isolate the component boundary
ReversibleCheck Settings for the line status and test the carrier QR/app on stable Wi-Fi. Use a known reference input or manufacturer test and compare the result. Boundary to separate: carrier provisioning versus device lock, line selection and activation network.
Correct only the proven cause
ReversibleHave the carrier reissue provisioning or correct the default voice/data line. Correct the setting, calibration or component proven by that comparison.
Verify and stop safely
ReversibleRepeat with the reference and a normal real-world case. Do not delete the only eSIM until the carrier confirms a replacement activation path.
Evidence ledger
Sources behind this answer
Visible sources support the visible claims. Home Product Support records the publisher, the fact used and the review date; community reports can suggest an issue but do not become a published fact on their own.
Exact questions
Common follow-ups
What should I check first when iPhone eSIM or cellular line has this problem?+
Check Settings for the line status and test the carrier QR/app on stable Wi-Fi.
Why not factory-reset immediately?+
The useful boundary is carrier provisioning versus device lock, line selection and activation network. A reset can erase state without proving which side failed.
When should I stop troubleshooting?+
do not delete the only eSIM until the carrier confirms a replacement activation path.
Answer for the exact device and software version shown above.