Nathan calls in but doesn't say much of anything serious, maybe shares a funny story he's read somewhere on the internet back home.
George calls in to crack a few jokes at Lee, and to thank Lorcan and Lee for doing such an awesome job with the radio station and really taking charge of it!
Godric does not call in because he does not understand what you're supposed to do. It's possible he pokes at the microphone a couple times, which might make some noise, but doesn't say anything and then walks away because what IS this thing anyway?!
Theodore does not call in....obvs.
Jasper doesn't either, but pretend he left a note under the door saying he thought the idea was pretty cool.