Immediately after Apple rolled out the iOS 10 public update last evening in India, there were uproars on Twitter with some people complaining that the update was bricking their iPhone.
Don’t upgrade to iOS 10. It is bricking devices. My iPhone got bricked. https://t.co/BfHTd65DuL
— Rajat Agrawal (@rajatagr) September 13, 2016
This lead to many to halt updating their phones, or tablets immediately and watch before it was clear that the storm had settled. If you are still on iOS 9 and waiting to go ahead with the update, and want to be absolutely safe, you can update via iTunes as it seems the problem was with the OTA update and no more.
However, beyond the phones and tablets being bricked, looks like iOS 10 is causing more problems. Users of China Mobile are complaining that their iPhone has lost the support for VoLTE once they updated to iOS 10. China Mobile has been quick to accept that this is due to a minor incompatibility with their network which has risen post the update, but a simple restart or even putting the phone in Airplane Mode and then back on cellular will resolve.
If you are not getting VoLTE support, you just need to re-register your device basically on the network and that should do the trick and get it working. If that is not working, then perhaps downgrading your iPhone is another option. We would though ask you to be patient and call up the customer support and wait for the issue to be resolved rather than going ahead with downgrading the device immediately.