I am trying to integrate Parse with Sinch using the source code in Github. Everything works fine as long as the user is signed up using the Android API ParseUser.signUpInBackground(). However when I create a Parse user using Parse's website, I am unable to send messages to the newly created user. I am getting an error "User does not exist". This happens too if the user has signed up using Facebook and Twitter. I also observed that when you do a login to the newly created user then the issue is gone.
This is because sinch doesnt know about that user yet, you need to login in an app and start the client once so sinch know where to send messages and incoming call notifications.