PLATFORM AND VERSION iOS Development environment: Xcode 15.4, macOS 14.5 Run-time configuration: iOS 17.5.1  DESCRIPTION OF PROBLEM We use PushKit to push offline messages of Voip, and use Voip notifications to bind with CallKit to implement Voip call functions. During the test, we found that when the app is in the background or the screen is locked, Voip messages cannot reach the device stably. After several consecutive calls, the phone will not be able to receive new messages for a period of time. Only after the App is uninstalled and reinstalled can it continue to receive messages.  STEPS TO REPRODUCE 1: Open the app and log in successfully 2: Push the app to the background, kill it or lock the screen 3: Use another user to make a voip call to this device 4: Repeated calls