The com.innovaphone.notificationhandler is used to communicate with the launcher itself and handles callbacks from com.innovaphone.launcher.
The client provideApi function is used to access the Api:
var notificationHandlerApi = start.provideApi("com.innovaphone.notificationhandler");This callback is triggered through the api on user interaction with the notification.
notificationHandlerApi.onmessage.attach(function (consumer, obj) {
    if (obj.msg.mt == "LocalNotificationClicked") {
        if (obj.msg.action == "accept") {       // accepted        
        }
        else if (obj.msg.action == "reject") {  // rejected            
        }
        else if (obj.msg.action == "reply") {   // reply with input
            // obj.msg.replyText contains the text
        }
        else {                                  // default action, e.g. open the current chat/call/etc.
        }
    }
});| string src | The src for this notification. | 
| string action | Can be empty or accept|reject|reply. | 
| string replyText | The reply text. | 
| For C++ App take a look into C++ AppWebsocket | 
| For Javascript Generic take a look into Javascript config.json | 
Announce com.innovaphone.notificationhandler in your App. For example in Generic Javascript App via config.json
    "apis": {
            "vendor-yourappname": {
                "com.innovaphone.notificationhandler": {
            "info": {}
            }
        }
    }
This example shows how to use com.innovaphone.notificationhandler with com.innovaphone.launcher on clientside Framework.
    var notificationHandlerApi = start.provideApi("com.innovaphone.notificationhandler");
    notificationHandlerApi.onmessage.attach(function (sender, obj) {
        if (obj.msg.mt == "LocalNotificationClicked") {
            console.log(obj);
        }
    });
    var dis = start.consumeApi("com.innovaphone.launcher");
    var call = {};
    call.dn = "Max Muster";
    call.uri = "maxmuster@domain.de";
    call.e164 = "1234560";
    call.id = 1;
    var title = "Call by " + (call.dn || call.uri || call.e164 || "Unknown");
    dis.send({ mt: "AddLocalNotification", src: "ApiTester", title: title, text: "This is a test", acceptTitle: "Annehmen", rejectTitle: "Ablehnen" }, "*", call.id.toString());