After watching The Bourne Ultimatum so many times, I noticed something I didn't really pick up on before. Throughout the entire movie Bourne attempts to keep quiet about what he's doing, trying to be as discreet as possible, when trying to save Simon at Waterloo, or saving Nicki from the assassin, he tries to not let his position be known. And yet, even after revealing to Pamela Landy that he is watching her, they still don't know where he is.
However, when he opens Vosen's safe and talks to him, he gives away his position by countering Noah's assertion that he is in his office by saying "If you were in your office we'd be having this conversation face to face.".
This is the part that confuses me the most. If he wanted to have the most time to analyze the data and escape, why would he deliberately choose to reveal his position to Vosen, therby alerting everybody else? And furthermore, when Vosen asks his underling to check the safe, it's clear Bourne leaves the safe completely open.