Thanks for the update.
[quote='855119022, DTS Engineer, /thread/797563?answerId=855119022#855119022']
Oddly, as far as I can tell, the issue has basically been present from the beginning, so I'm not sure why I haven't heard of this before. Are you creating CXProvider on a background thread? I generally recommend using the main thread for CallKit and PushKit, and it's possible that initializing them on a background thread might make this problem more likely due to differences in thread priority.
[/quote]
Here as mentioned in the feedback, the CallKit gets initialised is in Main queue, please refer the below code:
callkitProvider = [[CXProvider alloc] initWithConfiguration:config];
[callkitProvider setDelegate:self queue:dispatch_get_main_queue()];
But client has getting initiated in secondary queue for the PushKit,
voipRegistry = [[PKPushRegistry alloc] initWithQueue: voipPushNotificationQueue];
does this could lead to the issue regarding not received providerDidBegin(_:) delegate ?