Use FusedLocationServiceApi without internet conne

Question

i've recently created a GPS Location Service which uses FusedLocationProviderAPI from GooglePlayServiceAPI. Everything is working fine except receiving coordinates without an enabled internet connection.

I did a lot of research why this isn't working without an internet connection and i still don't know why. When I am connected to my Wifi it is working fine and the location is being updated perfectly. But when I restart my device and disable wifi and mobile internet it isn't working anymore. When I start the location updates while I am connected to the internet and disable my internet connection the location update is still working. Somehow, it changes then from the internet provider to GPS provider.

Am I doing anything wrong or is it a bug that I am not able to get coordinates without an internet connection.