Some users have noticed that after they upgrade their iOS to 9.2.1 from 9.2, Siri is not working. This is especially an issue for those users that use Siri to initiate calls on their phones via voice control. Issues have also been observed when trying to use Siri to create reminders. The issue happens irrespective of the iPhone models. If you are on iphone 5 or iphone 6 models and are experiencing this issue with Siri, Please proceed with the following steps:
Make sure your internet connection is correct and strong, whether it is Wi-Fi or Cellular or LTE. Siri issues have been seen with slow internet speed. Reset your network settings and then try using your phone once you have verified the strength of the signal. If you are using your device and have checked the internet speed and still experiencing the issues, please proceed to the next steps.
Step ->1
Back up your phone and save your data. If you have questions around backups, please refer to the Apple knowledge base.
Step- >2
Put your phone into DFU Mode. Connect your iPhone to your computer and open iTunes (if it doesn’t open automatically). Hold down both the top (sleep/wake) and home buttons for exactly 10 seconds, then release the top (sleep/wake) button but keep holding the home button until iTunes displays a message stating that a phone in recovery mode has been discovered.
Step-> 3
Press the restore button and allow the phone to complete the restoration process. You can restore from your backup using the this DFU mode. If restoring from backup doesn’t work for you, your only choice is to repeat steps 1 and 2 and try restoring it as a new phone. It’s a hassle to set it up as a “New phone” but most problems seem to be mitigated by choosing it.
Optional: If you have a newer device such as iPhone 6/Plus, you can try to upgrade it into the 9.3 beta as the Siri problem does not seem to happening in that release. You also can choose to downgrade back to iOS 9.2 by following the steps from the article below.
https://dennypedia.com/ios-9-2-1-update-causing-problems-how-to-downgrade-to-ios-9-2/