title: Can I use both GCM and FCM in my app?
body: <p>I have an android project in which GCM is implemented. Back-end (server) is already coded suitably with GCM. </p>
  
  <p>Now is it possible to add firebase (FCM) in my project and work in parallel with GCM? I cant migrate to FCM because it is impossible to change my back-end code as it is a big project and too much code is there. Has anyone done something like this?</p>
  
  <p>Please help. Thanks in advance.   </p>