Mobile APP Expert

We need someone with a deep understanding of notifications and background tasks to resolve issue with our app. Our app is not receiving silent notifications while another app is in the foreground. We use FCM to send silent notifications for incoming voip call data, and this is working perfectly when our app is in the foreground, background, suspended, or when the phone is locked. However, we are facing difficulties delivering these notifications when the user is using another app such as email or photos.