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Modern Landline Phone Systems-How does it work?

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  • Modern Landline Phone Systems-How does it work?

    I know the cellular system gets all the attention now a days. But the landline phone system still going strong in the western world.

    Does anyone know how it works now a days? From what I've been able to find. The government in the USA have given them permission (2014 or so) to move away from the old digital phone system and start turning the whole phone system into an IP based system. Is this true? How are they going to turn it from it current form into the next generation, etc?

    https://en.wikipedia.org/wiki/Plain_...ephone_service

    http://www.instructables.com/id/Chea...ivate-Telepho/
    Last edited by Lance G; 04-04-2017, 04:40 PM.

  • #2
    Originally posted by Lance G View Post
    I know the cellular system gets all the attention now a days. But the landline phone system still going strong in the western world.

    Does anyone know how it works now a days? From what I've been able to find. The government in the USA have given them permission (2014 or so) to move away from the old digital phone system and start turning the whole phone system into an IP based system. Is this true? How are they going to turn it from it current form into the next generation, etc?

    https://en.wikipedia.org/wiki/Plain_...ephone_service
    Well if it's an IP based system.. that means a higher level of abstraction - it's going to be done not on the basis of the physical world but on the basis of internet communications. So the idea of a 'telephone network' will no longer mean a physical network, thousands of miles of cables, switch-stations, etc... but rather a software protocol that telephone-like devices connected to the internet can implement in order to be able to call each other and allow the exchange of voice communication.

    In that case, how it's actually implemented in hardware terms will be irrelevant and decoupled from the idea of a telephone network itself.. I mean you can theoretically implement the internet and its technologies via 19th century telegraph wires, relay stations and manual operators (albeit it would be impractical of course due to the abysmal data transfer rates).

    The telephone network would basically just be part of the internet and employ all the same physical infrastructure that the rest of the internet does; all 'calls' would be controlled and routed through fibre-optic undersea cabling, satellites, copper wiring, and server parks just like all other internet data is.

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    • #3
      You mean to tell me that US has different network for telephones and the internet?

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      • #4
        As PEMM said. Don't know about the US but I have no copper telephone lines anymore since...2000 (DSL)?

        That's what the splitter was for, to separate telephone and internet lines.

        In the meantime we have internet and telephone per cable. The traditional TAE sockets remain unused.


        Though in rural areas this might look otherwise.



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        • #5
          Originally posted by PEMM View Post
          You mean to tell me that US has different network for telephones and the internet?
          I guess it would depend on your provider and chosen service.

          The downside of not having access to a classical landline is that the phones won't work during power outages.

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          • #6
            Yes the US uses 2 different systems for TCP and "land lines", many of us have gone full TCP and have our phone service as a (small) part of our data service, many more still have "land lines".

            All the backbone traffic is TCP/IP (it IS a Bell protocol), for those with old analog sets the Central office "de-muxes" the signal and translates it to the analog signal on your copper wires.

            The big (and it is BIG) difference in the two technologies is that the old "land lines" connected phone-A with phone-B over a physical set of wires (with a few amps tossed in), the modern packet switched world (TCP/IP rules - suck it Token Ring) a single medium handles a large number of sessions simultaneously, the traffic being broken down into small "packets". This can be the airwaves (Cellular) a pair of copper wires (DSL), a Co-Ax cable (like your TV), or Fiber. Phone-A spits packets into the torrent of data traffic going past, Phone-B gets those packets routed to it, re-assembles them (in the correct order, checking for missed packets).

            If you really want to know - TCP/IP https://books.google.com/books/about...kp_cover&hl=en


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            • #7
              I've had to learn the way current and some past architectures for telephony and data transmission worked. It was boring so I've forgotten most of it already.
              The gist with switching from one to another is that they're both run in parallel for a while until the older one is phased out.
              The biggest changes were that we went from analogue to digital and we gradually went from circuit switching to fully packet switching:

              IP based networks are simple and don't care what backbone you use to transport the data on.
              For the older systems you can just google for their architecture if you're interested in the types of systems had to be run in order to provide the services.
              The biggest challenge for packet switched multimedia services is the quality of service, since data packets share resources, can take different paths through a network and out of the box there were no concepts to store connection state information along the way.

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              • #8
                Originally posted by harryc View Post
                All the backbone traffic is TCP/IP (it IS a Bell protocol), for those with old analog sets the Central office "de-muxes" the signal and translates it to the analog signal on your copper wires.
                So it's the same as elsewhere. It would have been cool, if you still had those automatic relay stations around.

                I worked as a technicial for local network company and it was all digital aside from the last link. New houses and apartments were connected to network via fiber optics. I still got to repair few old copper cables (largest had 400 pairs) that still had paper insulation.

                Originally posted by Sniffit View Post
                The downside of not having access to a classical landline is that the phones won't work during power outages.
                Usually you have emergency power (batteries) in the stations, so It's not a problem unless the outage lasts for hours. Having a landline today won't change that.

                Which I can't remember ever experiencing. But we did once manage to cut communications from part of a town for two days...

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                • #9
                  More info on the beginning of the end of the copper line, physical switch and substation in the landline busy:

                  https://arstechnica.com/information-...s-customers/3/

                  http://boards.straightdope.com/sdmb/...d.php?t=526988

                  Anyone know any good books or website on how the MODERN landline phone systems works?

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                  • #10
                    At what level ? the general theory, and much of the particular practice, is outlined in Comer - TCP/IP https://books.google.com/books/about...kp_cover&hl=en

                    A
                    BIG feature of the 7 layer model is the ability to transmit over multiple types of physical media and equipment. My current blade servers are from Cisco and use one physical cable to pass all the traffic (encapsulating stuff from the fiber SAN). Your voice traffic is just one small part of one connection sharing wires and fibers with all the other data.

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                    • #11
                      Originally posted by Lance G View Post
                      I know the cellular system gets all the attention now a days. But the landline phone system still going strong in the western world.
                      Is this the case for most people on this forum I wonder?

                      - I hardly ever use a landline phone. I don't think I know any friends that have a landline phone so it has become quite redundant.
                      - Outdoors I sometimes switch to 4g communications because I have a lot more data to spend than minutes.
                      - In office I have no idea about the cellular system but I only ever used it for internal communication as last resort.

                      What greatly angered me a few years ago is that we had som communications companies that wouldn't offer a reasonable internet subscription without linking it to a useless telephone landline subscription. I get the reasoning because you use the infrastructure but it is still a redundant paid for service. If I'm not using my cellphone I'm using skype or google hangout on my laptop.

                      So far the main benefit I have discovered about a landline is that grandmothers somehow seem less capable of remembering cellphone numbers.

                      What I find infuriating is how, in 2017, the landline still costs me more when I want to make "international" calls. Of course, there are a million ways to prevent this by using other communication means, but it really defeats the purpose of a landline for me.

                      I wonder if landlines can be a competitor for other communication methods but for a simple consumer they seem like a waste of cash to me.

                      *

                      I know my parents do not use the old landline infrastructure, internet/tv/landine all goes via coax (?). I doubt new neighborhoods/houses are connected to the old infrastructure.
                      Last edited by OrangeWolf; 10-04-2017, 11:46 PM.

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