[ionic v6] IOS Backgroud mode audio call microphone dont work

Hi guys,

i have a button fab that opens a modal with a frame inside in that frame i have a provider who help me to support users and there is possibility to do a voip call. When call starts IOS asks me for microphone permissions and call works file, operator listen me and i listen him, but if i close app in background operator stops to listen me probably because microphone stop works when app is in background. Can some one tell me how to resolve this problem? The problem is present only on IOS devices