Why not simply ask folks at the Mark Twain House, where the problematic
phone can still be seen, and I believe along with a terse note written by
commenting on the fickle nature of the beast? (860) 247-0998.
The very first public phone service in the nation began in New Haven,
Hartford, but since Sam was very concerned about being up-to-date especially
in the socially competitive atmosphere of Nook Farm, just to HAVE such a
device, whether or not it was any practical use, is, I suspect, what really
counted in the end.
Hope this helps!