So, if it's authenticity you want, you'll have to incorporate some sort of noise generator on the lines. Telco quality is much better today than 40 years ago (although you may not think so). I recall that calling Sunnyvale from Los Gatos (or vice-versa) was a real adventure in connectivity. Los Gatos was GTE; Sunnyvale was AT&T. I think that someone once told me that the network interconnect was acoustic (I don't know if that was true). But you might as well have been calling Boston, for the line quality.
--Chuck
