Could anyone give me a tip on how to build a layout like in the following picture?

The application i’m working on has absolutely nothing to do with VoIP but I’m trying to build something like this. One fixed toolbar at the bottom, an interchangeable middle pane with listviews, scrollviews or other, and another toolbar at the top which would change depending on the button selected on the bottom bar.
Also, would it be possible and good practice to keep all of this within a single activity?
You should NOT build an interface like this. Don’t use bottom bars! Don’t use labelled back buttons on action views!
You should read the Android design guidelines and then work with tab views… and other stuff referenced there and build an Android app.