Telephone was invented in 1876. The California Electrical Works of S.F. built the first successful long distance telephone line in 1878 from French Corral, California to Milton, California, .. a distance of 60 miles, to facilitate control over placer flumes used in mining. This line, like many early lines was single conductor. Interchange with Western Union was made via a line from Nevada City to North San Juan, giving the most remote locations on the Ridge Telephone Company line direct connection with the entire world. All this in 1878.
I suspect the operations of the SV Tel Co. and the Ridge Tel Co. are similar. They operated to benefit the company communications, but served a second purpose as a utility to the communities it served along its route. I found a piece of a Cal. Elec. Works insulator while down there looking at the SV. These guys were LARGE electrical contractors and did work on the Collins Telegraph, the military telegraphs, their equipment has been found in use as far away as Alaska and Texas.
It is highly possible that the SV started out with phones if the Ridge line was doing it successfully some 12 years before the SV started putting down track. Maybe even had work done by them ??? I have no proof of this, .. just saying it is quite possible. The Mother Lode country and Baker City were not so far away from SF in the Robber Baron days.
By 1910, ground return, or single wire lines for phone, were pretty much a thing of the past. Cross talk and echo necessitated a "metallic ground" (a second wire). Old timers said the early phones sounded like you were talking to someone standing at the bottom of a well.
What I am finding in the field is not 1890's telegraph glass like CD 145's, but rather telephone "pony" glass like CD 102's and 106's. One might think the SV would have got their line materials from the UP, but the evidence shows such was not the case. The UP lines are distinctly telegraph, while the SV lines are distinctly the much lighter phone stuff. More investigation needs to be done, but that is what I have found so far.
Got my $#@! Ferrell book out. Maybe I can find a pic or two in there for reference ?
SV Tel Dude