phew! been a really long time since the last post. I sort of stopped working on the VoIP idea.
What's new is dalvik bytecode injection. I managed to inject instructions in memory for an Android app.
According to Andy McFadden (the guy who wrote much of the VM), I am most probably the first person to do this. Encouraged, I am starting a project to have a comprehensive injection library for Dalvik.
This is the Issue tracker of Android that is currently active with the discussion