     func getRingbackUri(_type: String) -> NSURL? {
         let fileBundle: String = "incallmanager_ringback"
         let fileBundleExt: String = "mp3"
-        let fileSysWithExt: String = "vc~ringing.caf"
-        let fileSysPath: String = "/System/Library/Audio/UISounds"
+        //let fileSysWithExt: String = "vc~ringing.caf" // --- ringtone of facetine, but can't play it.
+        //let fileSysPath: String = "/System/Library/Audio/UISounds"
+        let fileSysWithExt: String = "Marimba.m4r"
+        let fileSysPath: String = "/Library/Ringtones"
         let type = (_type == "" || _type == "_DEFAULT_" ? fileSysWithExt : _type) // --- you can't get default user perfrence sound in ios
         return self.getAudioUri(type, fileBundle, fileBundleExt, fileSysWithExt, fileSysPath, &self.bundleRingbackUri, &self.defaultRingbackUri)
     }

        let filename = player.url?.URLByDeletingPathExtension?.lastPathComponent
        if filename == self.bundleBusytoneUri?.URLByDeletingPathExtension?.lastPathComponent
            || filename == self.defaultBusytoneUri?.URLByDeletingPathExtension?.lastPathComponent {
            self.stopBusytone()
            self.stop("")
        }
        print("finished playing: \(filename)")

        print("startProximitySensor()")
        self.currentDevice.proximityMonitoringEnabled = true

        //self.stopObserve(self, name: UIDeviceProximityStateDidChangeNotification, object: self.currentDevice)
        self.startObserve(UIDeviceProximityStateDidChangeNotification, object: self.currentDevice, queue: nil) { notification in
            let state: Bool = self.currentDevice.proximityState
            if state != self.proximityIsNear {
                print("Proximity Changed. isNear: \(state)")
                self.proximityIsNear = state
                self.bridge.eventDispatcher.sendDeviceEventWithName("Proximity", body: ["isNear": state])
            }
        }
        
        self.isProximityRegistered = true
