how to get the incoming call number by using callkit

When using CallKit's Call Blocking & Identification feature (new in iOS 10), phone numbers to be blocked or identified are loaded by your app's Call Directory extension prior to an incoming call and the phone numbers are stored by the system. Then, when an incoming call arrives, this stored data is consulted by the system and an incoming call may either be blocked or identified in the incoming call UI with the label provided.

For privacy and performance reasons, Call Directory app extensions are not launched when incoming calls arrive and an app extension cannot retrieve the phone number for an incoming call.