Use AVAudioPlayer for sound play instead of PlaySystemSound. This allows to control the volume of the notifications from within the app.

Classes/LinphoneManager.h

@@ -98,8 +98,6 @@ struct NetworkReachabilityContext {
 @end
 
 typedef struct _LinphoneManagerSounds {
-    SystemSoundID call;
-    SystemSoundID message;
     SystemSoundID vibrate;
 } LinphoneManagerSounds;
 
@@ -132,6 +130,7 @@ typedef struct _LinphoneManagerSounds {
 + (NSString *)getUserAgent;
 + (int)unreadMessageCount;
 
+- (void)playMessageSound;
 - (void)resetLinphoneCore;
 - (void)startLibLinphone;
 - (void)destroyLibLinphone;

Classes/LinphoneManager.m

@@ -38,6 +38,8 @@
 
 #import "LinphoneIOSVersion.h"
 
+#import <AVFoundation/AVAudioPlayer.h>
+
 #define LINPHONE_LOGS_MAX_ENTRY 5000
 
 static void audioRouteChangeListenerCallback (
@@ -99,6 +101,12 @@ NSString *const kLinphoneInternalChatDBFilename = @"linphone_chats.db";
 	[super dealloc];
 }
 @end
+
+
+@interface LinphoneManager ()
+@property (retain, nonatomic) AVAudioPlayer* messagePlayer;
+@end
+
 @implementation LinphoneManager
 
 @synthesize connectivity;
@@ -247,26 +255,13 @@ struct codec_name_pref_table codec_pref_table[]={
 			[LinphoneLogger logc:LinphoneLoggerError format:"cannot register route change handler [%ld]",lStatus];
 		}
 
-		// Sounds
-		{
-			NSString *path = [[NSBundle mainBundle] pathForResource:@"ring" ofType:@"wav"];
-			sounds.call = 0;
-			OSStatus status = AudioServicesCreateSystemSoundID((CFURLRef)[NSURL fileURLWithPath:path], &sounds.call);
-			if(status != 0){
-				[LinphoneLogger log:LinphoneLoggerWarning format:@"Can't set \"call\" system sound"];
-			}
-		}
-		{
-			NSString *path = [[NSBundle mainBundle] pathForResource:@"msg" ofType:@"wav"];
-			sounds.message = 0;
-			OSStatus status = AudioServicesCreateSystemSoundID((CFURLRef)[NSURL fileURLWithPath:path], &sounds.message);
-			if(status != 0){
-				[LinphoneLogger log:LinphoneLoggerWarning format:@"Can't set \"message\" system sound"];
-			}
-		}
-		sounds.vibrate = kSystemSoundID_Vibrate;
 
-		logs = [[NSMutableArray alloc] init];
+        NSString *path = [[NSBundle mainBundle] pathForResource:@"msg" ofType:@"wav"];
+        self.messagePlayer = [[[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL URLWithString:path] error:nil] autorelease];
+
+        sounds.vibrate = kSystemSoundID_Vibrate;
+        
+        logs = [[NSMutableArray alloc] init];
 		database = NULL;
 		speakerEnabled = FALSE;
 		bluetoothEnabled = FALSE;
@@ -294,13 +289,6 @@ struct codec_name_pref_table codec_pref_table[]={
 }
 
 - (void)dealloc {
-	if(sounds.call) {
-		AudioServicesDisposeSystemSoundID(sounds.call);
-	}
-	if(sounds.message) {
-		AudioServicesDisposeSystemSoundID(sounds.message);
-	}
-
 	[fastAddressBook release];
 	[logs release];
 
@@ -1521,6 +1509,14 @@ static int comp_call_id(const LinphoneCall* call , const char *callid) {
 	return YES;
 }
 
+- (void)playMessageSound {
+    BOOL success = [self.messagePlayer play];
+    if( !success ){
+        Linphone_err(@"Could not play the message sound");
+    }
+    AudioServicesPlaySystemSound([LinphoneManager instance].sounds.vibrate);
+}
+
 static int comp_call_state_paused  (const LinphoneCall* call, const void* param) {
 	return linphone_call_get_state(call) != LinphoneCallPaused;
 }

Classes/PhoneMainView.m

@@ -675,8 +675,7 @@ static RootViewManager* rootViewManagerInstance = nil;
 - (void)playMessageSound {
     if ([UIApplication sharedApplication].applicationState != UIApplicationStateBackground) {
         if(![self removeInhibitedEvent:kLinphoneTextReceived]) {
-            AudioServicesPlaySystemSound([LinphoneManager instance].sounds.message);
-            AudioServicesPlaySystemSound([LinphoneManager instance].sounds.vibrate);
+            [[LinphoneManager instance] playMessageSound];
         }
     }
 }