I am creating a taxi driver app in android. When passenger requests for a ride, the request is posted to the server. Now, the server sends the request to the nearby taxi driver. Driver app has an activity with siren which has to be triggered on receiving the request. So, whenever a request arrives, I have to show the siren activity with siren sound. How can this functionality be achieved? I have to show the activity even if the driver app is in background.

Thanks.