Using a Fritz!Fon handset for Volumio. Weird!

I don’t know where to put this message. It is about the Fritzbox; most messages about the Fritzbox appear in help and support.
So I have a Fritz!Fon (telephone handset) too. And I noticed that I can use Volumio with this handset. I use the Fritz Media server and the Options button. It has its limitations, but it works! I made two pictures of this, in order to clarify.