If you know she listens in on your conversations I think I would be attempted to make some random not real phone calls, like discussing where or the best way to get rid of the body, what the aliens are planning or what the CIA just told you. Just done randomly, nothing to take away from the work at hand, but over a few weeks it will be interesting to hear what crazy stuff she repeats to others. Will driver her nuts and make her look crazy to boot when she starts nattering on to others about your "conversations". You are legally entitled to breaks by law and phone calls made on that time on your phone are no one's business.
Of course you won't have a clue as to what she's going on about and can just gape at her in amazement. If you are going to make the choice to blatantly eavesdrop on others then you hear what you hear.
Oh my! Wine out the nose hurts!!!! My little brother and I often discuss how to hide the bodies etc when we know people are eavesdropping...
This is a great idea, but if you want to up the ante, somewhat, start the story, and then drop your voice to a whisper, but say certain key words a little louder.
You could make up a story about your neighbors brand new body suit and how it was a surprise for her husband and how she had to hide it from him. Key words here being body, hiding and him.
It will drive her crazy trying to hear what you are talking about, or she will just fill in the blanks with what she thinks she knows.
We have someone like this where we work, and her nose is ALWAYS where it doesn't belong. She talks loud enough for everyone to hear whether they want to or not, and if she can hear what you are saying, she will add her two sense, even if you are not talking to her.
There are a few people who like to read on lunch, me being one of them. I will either sit with another reader, or sit by myself. I find it rude if a reader sits with the talkers and doesn't talk, and if you sit with me, don't get upset if I don't talk. One lunch, at the table I was at were 3 readers and one empty seat, while there were many talking tables that had empty spots. Guess who sat with us. I simply said, "We're reading, no talking." I received glances of thanks from the other 2 readers, and "the mouthy one" while not silent, definately talked very little.