At the start, Vanessa calls Maureen as Maureen is in a taxi. Vanessa says something like "I'll come to you, let's meet for lunch tomorrow" but this is before she knows/assumes that Maureen is in New York. Wasn't Maureen a professor at Cambridge(?) University, isn't that in England? How was Vanessa going to get to England if she wanted to meet Maureen for lunch the next day when she didn't know she was in New York?
Deanna Maureen didn't teach at Cambridge University. She was at Harvard which is in Cambridge, Massachusetts. They never say Harvard in the book but it's just known that Cambridge is code for Harvard in the U.S. Plus she lived in Boston.
ViewSkyBlue When Maureen answers the phone, Vanessa overhears the New York address Maureen gives to the taxi driver. This is confirmation to Vanessa that Maureen is already in town for her summer teaching course at Columbia.