Mordor Communication

[Bingo]

I haven't read Osanwe-Kenta, but I just remembered that there is some kind of long distance communication associated with the one ring.

For in the day that Sauron first put on the One, Celebrimbor, maker of the Three, was aware of him, and from afar he heard him speak these words, and so his evil purposes were revealed.

But all that has been wrought by those who wield the Three will turn to their undoing, and their minds and hearts will become revealed to Sauron, if he regains the One.

So maybe, if Sauron holds the nine rings (or wears them on his nine fingers?) he might have a mental link with each of the nazgûl.