The cell phone only said "Work." Drew was torn. If she let it go to voicemail, she might be over it, but if she answered, she could just say she was at school or off on the skating trip and get out of it for the week.
Ultimately, she decided that it was safer to ignore it, better not to risk being called in, which was likely. After a few rings it stopped and, went to voicemail.
With any luck she would not be here that long and it wouldn't matter anyway. It would've be interesting to see if and when the real Michelle got back if she had decided to work - who the hell worked for her?