What It Is
A telephone exchange, according to Wikipedia, is a "telecommunications system used in the public switched telephone network or in large enterprises." In these exchanges, the newer systems have electronic components and the older have manual human operators, each of which connect telephone subscriber lines to their designated calls.
(Photo courtesy of http://www.bbc.co.uk/staticarchive/543871ca280c2dfdc97037007b5df0df91e8e4b8.jpg)
How It WorksThe Public Switched Telephone Network (PSTN), or the Plain Old Telephone Service (POTS) as it's also referred to as, is the network that all landline calls are made through. According to Dave Roos of HowStuffWorks.com, this system relies on circuit switching, a process of routing the phone call through switches to connect the callers.
Before the 1960s, phone calls traveled across copper wire as analog signals. Since every phone call needed its own copper wire manually connecting the two phones, phone operators needed to be there to assist with the calls. According to Roos, the "operators sat at a switchboard, literally connecting one piece of copper wire to another so that the call could travel across town or across the country. Long-distance calls were comparatively expensive because you were renting the use of a very long piece of copper wire every time you made a call."
(Photo courtesy of http://www.faxswitch.com/images/Switchboard.jpg)
Now it gets even more interesting because in the the 1960s, the system was updated to fiber-optic cables, but the process was still pretty much the same. Thousands of calls may be able to share the same line, but circuit-switching still requires a circuit, or basic connection, to stay open for the entirety of the phone call.
(Photo courtesy of http://ccs4all.com/wp-content/uploads/2014/07/2.jpg)
When the call goes to businesses, however, an additional system is needed. Company departments and employees tend to have their own extensions within the business' telephone number, so the calls would be operated through the company or organization's personal telephone exchange on campus. This exchange is also known as a private branch exchange (PBX).
(A PBX, circa 1900. Photo courtesy of http://www.nicherons.com/images/pbx.jpg)
If you're going to call internationally, you need to go through one or two more steps. "The call needs to be routed through your long-distance phone carrier to another country's long-distance phone carrier. To signal such a switch, you have to dial two separate numbers, your country's exit code (or international access code) and the corresponding country code of the place you're calling" (Roos).
A Short History
Research done by people on Wikipedia has found that the first exchange built by a single person was built in 1877 by Thomas Edison's Hungarian colleague, Tivadar Puskás. An experimental version came next, also in 1877, and was built by the Bell Telephone Company in Boston and inspired by Puskás. Germany quickly jumped on this and opened the world's first commercial telephone exchange in Friedrichsberg in November of that same year.
(Germany's first telephone exchange in Berlin, 1881. Photo courtesy of http://www.siemens.com/history/en/news/1067_telephone-exchange.htm)
It wasn't long after that, in January of 1878, that the US opened their first commercial exchange by George W. Coy. The National Historic Landmarks Program puts it lovingly that this first switchboard built in the US by Coy was made only of "carriage bolts, handles from teapot lids and bustle wire." It's hard to believe that things were able to escalate to the impressive level of technology that they have today from something that meager. But that's the nuts and bolts of it.
(One of the first switchboards, circa 1878. Photo courtesy of http://inventors.about.com/od/bstartinventors/a/telephone_2.htm)
Why You Need It
You may not need it, per say, but you certainly do want it. You would never be out of conversation points at a party, you can play an epic game of telephone, and it could also be an eclectic antique piece to put in your library. Any way you go about it, it will only put you out less than $300 (no tax in Oregon!). If not, come by and see it anyways. You don't want it to get lonely, do you?
- Roos, Dave. "How Telephone Country Codes Work." How Stuff Works. HowStuffWorks, 07 Feb. 2008. Web. 02 Feb. 2015. <http://electronics.howstuffworks.com/telephone-country-codes1.htm>.
- "Telephone Exchange." Wikipedia. Wikimedia Foundation, 15 Jan. 2015. Web. 02 Feb. 2015. <http://en.wikipedia.org/wiki/Telephone_exchange>.
- "Withdrawl of National Historic Landmark Designation: Site of the First Telephone Exchange." National Historic Landmarks Program. National Park Service, n.d. Web. 02 Feb. 2015. <http://wayback.archive.org/web/20130302120900/http://www.cr.nps.gov/nhl/DOE_dedesignations/Telephone.htm>.