How to coalesce VOIP push notifications ?

Is there a ducument describing how to coalesce VIOP push notifications (PushKit) ? The pushkit documnetation says that Apple will make every effort to send them at high priority, does that mean they cannot be coalesced ?

Is setting priority to 5 make voip push coalesced ?

What is the default behaviour (default priority) when not specifying any priority when sending VOIP pushes?

All questions are related to the server-side push API

How to coalesce VOIP push notifications ?
 
 
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