Zoom phone muted when the app is minimized on Android

When I am on a Zoom phone call using my Android device, and I minimize the app or have it open in the background, the call goes silent like it's put on hold.  I cannot speak with the other party or hear them speaking to me until I maximize the app again.  This makes it difficult to look for information while speaking on the Zoom phone.  How do I keep the phone call active while the app is running in the background?