I am following this article and M Penades' answer building VoIP Notification Demo. I am able to register notification using didRegisterUserNotificationSettings and can get voip token from didUpdatePushCredentials.
But when I am using houston simulates sending notification to my device, I can get 1 push notification sent successfully message from console but no actions or logs on device side. It seems that didReceiveIncomingPushWithPayload never invoked.
P.S. I am using Xcode 7.3, iPhone 6(iOS 9.3) and iPad Mini(iOS 9.3) for development. Distributed Ad Hoc ipa for installation.
The codes posted here.
import UIKit
import PushKit
@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
let voipRegistry = PKPushRegistry(queue: dispatch_get_main_queue())
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
    // Override point for customization after application launch.
    //Enable all notification type. VoIP Notifications don't present a UI but we will use this to show local nofications later
    let notificationSettings = UIUserNotificationSettings(forTypes: [UIUserNotificationType.Alert, UIUserNotificationType.Badge, UIUserNotificationType.Sound] , categories: nil)
    //register the notification settings
    application.registerUserNotificationSettings(notificationSettings)
    //output what state the app is in. This will be used to see when the app is started in the background
    NSLog("app launched with state \(application.applicationState.stringValue)")
    return true
}
    func applicationWillTerminate(application: UIApplication) {
    // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
    //output to see when we terminate the app
    NSLog("app terminated")
}
}
extension AppDelegate {
func application(application: UIApplication, didRegisterUserNotificationSettings notificationSettings: UIUserNotificationSettings) {
    //register for voip notifications
    NSLog("didRegisterUserNotificationSettings called")
    voipRegistry.desiredPushTypes = Set([PKPushTypeVoIP])
    voipRegistry.delegate = self;
}
}
extension AppDelegate: PKPushRegistryDelegate {
func pushRegistry(registry: PKPushRegistry!, didUpdatePushCredentials credentials: PKPushCredentials!, forType type: String!) {
    NSLog("didUpdatePushCredentials called")
    //print out the VoIP token. We will use this to test the nofications.
    NSLog("voip token: \(credentials.token)")
}
func pushRegistry(registry: PKPushRegistry!, didReceiveIncomingPushWithPayload payload: PKPushPayload!, forType type: String!) {
    NSLog("didReceiveIncomingPushWithPayload called")
    let payloadDict = payload.dictionaryPayload["aps"] as? Dictionary<String, String>
    let message = payloadDict?["alert"]
    //present a local notifcation to visually see when we are recieving a VoIP Notification
    if UIApplication.sharedApplication().applicationState == UIApplicationState.Background {
        NSLog("incoming notificaiton from background")
        let localNotification = UILocalNotification();
        localNotification.alertBody = message
        localNotification.applicationIconBadgeNumber = 1;
        localNotification.soundName = UILocalNotificationDefaultSoundName;
        UIApplication.sharedApplication().presentLocalNotificationNow(localNotification);
    }
    else {
        NSLog("incoming notificaiton from frontend")
        dispatch_async(dispatch_get_main_queue(), { () -> Void in
            let alertController = UIAlertController(title: "Title", message: "This is UIAlertController default", preferredStyle: UIAlertControllerStyle.Alert)
            let cancelAction = UIAlertAction(title: "Cancel", style: UIAlertActionStyle.Cancel, handler: nil)
            let okAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: nil)
            alertController.addAction(cancelAction)
            alertController.addAction(okAction)
            UIApplication.sharedApplication().keyWindow?.rootViewController?.presentViewController(alertController, animated: true, completion: nil)
        })
    }
    NSLog("incoming voip notfication: \(payload.dictionaryPayload)")
}
func pushRegistry(registry: PKPushRegistry!, didInvalidatePushTokenForType type: String!) {
    NSLog("didInvalidatePushTokenForType called")
    NSLog("token invalidated")
}
} 
extension UIApplicationState {
//help to output a string instead of an enum number
var stringValue : String {
    get {
        switch(self) {
        case .Active:
            return "Active"
        case .Inactive:
            return "Inactive"
        case .Background:
            return "Background"
        }
    }
}
}
Any idea on how to receive such notification?