Speaking tubes - residential

I have the interior speaking tube whistle but would like more, as this one appears not to whistle. I also lack one for the front door.
Lonnie    lonniechu at gmail dot com
About speaking tubes (Wikipedia)

Mailboxes sold on eBay (top)
A mouthpiece at entry door of house similar to mine in my neighborhood (bottom)

The following are in .pdf format -
you'll need Adobe or Foxit Reader.

Speaking Tube Supplies

Patent lawsuit including speaking tube specs (to a degree)

Ferryboat Confession: story published in NY Times, 1900

Speaking tube whistle still in its wall in a home in San Francisco

  Three whistles in a row - communicated with three different locations in this large house.

Last updated February 7, 2009   lonniechu at gmail dot com