Name the symptom
Is the phone unable to see a SIM, unable to register, or connected but unable to load data? Are only incoming calls affected? Precise distinctions reduce the chance of applying a fix for the wrong problem.
Check low-risk causes
Review carrier incident information, account activity and allowance. Try a normal restart. On a dual-SIM phone, confirm the intended line is enabled. Compare another location if practical.
Avoid creating a second problem
Deleting an eSIM or resetting a phone can interrupt authentication and require a new activation. Do not use those steps simply because they appear in a generic forum response. Follow the provider’s recovery instructions.
Prepare for official support
Have the time, location, model, error and steps already tried available. Keep the case reference. This website cannot inspect a carrier account, restore a blocked line or remotely repair a network.