The plan here was to turn the console in a fully functional phone while still using the buttons of the Game Boy to play games, and on top of that it will see an extra battery tossed in there for good measure. At the moment it seems that flexoduss has managed to get calls working, but unfortunately due to the design of the Game Boy casing, the microphone is blocked and callers on the other end of the phone are unable to hear him.
It is a pretty interesting idea and while it might look silly putting the Game Boy to your ear to make/receive phone calls, there’s a certain degree of retro about the whole schebang that we find rather endearing (and nostalgic). For more information on flexoduss’ project, or if you’d like to contribute to it, pop on over to the XDA forums.