Decline incoming call with busy reason if more than one call

CHANGELOG.md

@@ -25,6 +25,7 @@ Group changes to describe their impact on the project, as follows:
 ### Changed
 - Account EXPIRES is now set to 1 month instead of 1 year for sip.linphone.org accounts
 - Replaced voice recordings file name by localized placeholder text, like for video conferences invitations
+- Decline incoming calls with Busy reason if there is at least another active call
 - Removed jetifier as it is not needed
 - Switched from gradle 7.5 to 8.0, requires JDK 17 (instead of 11)
 

app/src/main/java/org/linphone/core/CoreContext.kt

@@ -750,8 +750,13 @@ class CoreContext(
                 call.redirectTo(voiceMailAddress)
             }
         } else {
-            Log.i("[Context] Declining call $call")
-            call.decline(Reason.Declined)
+            val reason = if (core.callsNb > 1) {
+                Reason.Busy
+            } else {
+                Reason.Declined
+            }
+            Log.i("[Context] Declining call [$call] with reason [$reason]")
+            call.decline(reason)
         }
     }