How close do you have to be to a rail line to hear?

[wa8pyr]

That's Right! Even before I passed my Technicians License Exam, I was always curious about how railroads were able extend their communications. I wasn't too sure how PBX worked, but I assumed in some applications, it's like how Ship to Shore Operators are able to patch radios to landlines and vice versa.
Of course, most of time, the train crews and dispatchers are communicating via radio, so it's not exactly using PBX if both the train and dispatcher are using simplex radio to radio.

PBX in a railroad context is nothing more than a base station that is connected to the Public Switched Telephone Network so train crews can make phone calls, usually to places like a railroad support center (when they have customer switching issues), the PTC desk, the maintenance desk, and so on.

Dispatcher base stations are connected differently, to a phone line which is dedicated to the purpose; it’s always live and doesn’t require a number be dialed in the traditional sense, but rather a DTMF command which goes directly into the railroad comm system and alerts the dispatcher that somebody needs to talk.

Of course, these days some if not most large railroads are switching over to IP-based systems that use fiber or satellite, and leaving the traditional telephone network behind.

The variety of railroad comm systems would actually make an interesting article. Hmmmmm, maybe it’s time I started writing again.

 

[n7maq-1]

Fun fact, Southern Pacific Railroad had so much extra bandwidth on their microwave network they sold long distance service. That is what we now know as Sprint.


" Southern Pacific Communications and introduction of Sprint.
Sprint also traces its roots back to the Southern Pacific Railroad (SPR), which was founded in the 1860s as a subsidiary of the Southern Pacific Company (SPC). The company operated thousands of miles of track as well as telegraph wire that ran along those tracks. In the early 1970s, the company began looking for ways to use its existing communications lines for long-distance calling. This division of the business was named the Southern Pacific Communications Company. By the mid 1970s, SPC was beginning to take business away from AT&T, which held a monopoly at the time. A number of lawsuits between SPC and AT&T took place throughout the 1970s; the majority were decided in favor of increased competition. Prior attempts at offering long-distance voice services had not been approved by the U.S. Federal Communications Commission (FCC), although a fax service (called SpeedFAX) was permitted.

In the mid-1970s, SPC held a contest to select a new name for the company. The winning entry was “SPRINT”, an acronym for Southern Pacific Railroad Internal Networking Telephony."

The above is from The History of SPRINT (long distance, local, and wireless).

 

[ratboy]

I remember cursing SP/Sprint when my mother used it to call me from Florida, the quality was just awful. Hiss, voices in the background, echoes, it was pretty hard to take. I called her one time and it sounded like a local call, but anytime she called me, it was like an HF receiver in the winter, tuned to one of the Military freqs and hearing weak voices buried in the background hiss. At least the calls didn't have MacDill or some other punchy station key up and blast you out of your seat, and that "roger beep" they had, yikes.