Can GCM & FCM providers be active at the same time?

Question

Can both Google Cloud Messaging (GCM) and  Firebase Cloud Messaging (FCM) providers be active at the same time?

Answer 

No.  Currently only one provider for messaging (GCM or FCM) can be active at any time.  

Details on how to configure each Third-Party Provider can be found in the following articles:

• Setting up Firebase Cloud Messaging (Android)
• Setting up Google Cloud Messaging (Android)