The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 540
Fig. 472Front View- Automatic Selector … calling line should now be connected to No. 5679 line; but thisline may be engaged, in which case a busy buzz will be heardon the line. If the line is not engaged the caller presses aringing button, seen under the dial, which again earths the vertical line, energises a ringing relay at the…
Telephone
Internet Archive · Northeastern University Library · Public Domain Mark 1.0. Free to use for anything.
