have iphone 4s did the upgrade 9.1 and now phone won't call out or receive phone calls

Answer 1

Here are the tips to try to fix this issue:

1. Reset network settings.
2. Check date & time.
3. Activate / Deactivate Airplane mode.
4. Check if the sim card is active.
5. Do a fresh installation of the iOS 9.1 firmware.

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