Proguard - KaleyraVideo/VideoAndroidSDK GitHub Wiki
In case you are using Proguard you will need to define the following exception rules as shown here
# Kaleyra proprietary SDK
-keep class com.bandyer.** { *; }
-keep interface com.bandyer.** { *; }
-keep enum com.bandyer.** { *; }
-keep class com.kaleyra.** { *; }
-keep interface com.kaleyra.** { *; }
-keep enum com.kaleyra.** { *; }