My most sincere apologies to Barry Finn.
This thread was re-opened by "Blank" and Barry's was the first name to show up at the top of the page.
As for you're arguments.
Speaking Tubes are Ancient Egyptian in their origin and your suggestion that they were neither required nor used on board is only your opinion.
I am not the only one who knows this as the correct answer but I sincerely doubt, given the reactions here, that anyone else would dare go against the pack.

Once again.
My most sincere apologies to you, Barry Finn.