Reader note:"This screen capture from today's Space Station Live shows the ISS crew during this morning's call by Vladimir Putin to the ISS. Only Mastracchio & Swanson don't wear audio headsets. Is it some kind of sanction against Russia?"
Marc's note: The answer is no. There are only four places to plug in comm sets in the service module. Thanks to an astute reader for reminding us and everyone about this.
Keith's note: But NASA PAO has still not responded to our inquiry on this.