I tried giving Jonathan a call again this morning. I pressed the secretary a little bit and told her that he hadn't been responding to any communication and she said he was traveling last week. She said my best bet was still just to leave a message or try calling him throughout the day because he might actually be answering his phone for a brief period.
I'm getting extremely anxious because I have a job offer and they would seriously appreciate even a vague deadline on when I can tell them about the fulbright...