I tend to find that the most annoying thing on the HEX is not other people's calls but the louder-than-necessary TV playing in the background. In most cases this drowns out any conversations, telephonic or otherwise, going on around me.

As for using the phone, when I do I tend to try to keep my voice down or move to the area near the doors. I generally find that most people do the same. I am one of those who like things quiet around me but have never felt my privacy invaded on the HEX because of telephone over-usage. I have, on the other hand, complained to the ticket checkers about the volume of the TV.