I forked a messaging app on github and added my modification on top of it and it started to build an audience in my country because of the unique ad-on feature I have added. The app acts as an SMS gateway to country xyz.
Everything I have added on top of the original code will be on github as an open-source project except my SMS API/server details. Because that is what I understand with GPLv3 you need to give also the source code for free if you want to distribute the derivative project.
Now - will I break the GPLv3 if I distribute/publish on Android market the modified code with ads on it?