it actually turns out that the voice was not jeb he can just do the voice but no one knows who the voice is. the voice helps her because it cares it could just be her inner conscience that knows where to go and what to do.
Ok, i dont really know, but what i do know is that the voice is NOT jeb. I'm still reading the 5th book(Max), so maybe it says something about it in there...
The voice is Angel. It says in the last book. Think about it, she can read minds and send messages to people. Angel has always been Max's voice. Never Jeb. Jeb was trying to get Max to trust him more. Which we all know will NEVER happen.