The local loop is phone numbers in Traditional Telephony.
General topology some of the organizations and phone numbers in the public switched telephone network. local loop tip and ring pair there. But remember that local loop is just part of the larger architecture and it feeds into the whole thing now as a reminder the telephone number is highly geographic. And so what we’re gonna talk about right now as we go over the local loop are phone numbers that have a lot in common area code and the office code. So all of these phones that are part of the local the local connection are what we call the local loop we’ll all have those numbers as the same.
The real big difference will be in the station code
which identifies that circuit so we hear we have a layout generally of a local loop a couple of features or details about the local loop is analog. Now, these are almost always small connections. If you have a larger business it’s not likely that you’ll have an analog line coming in although it’s possible that you might have several. So we’re going to talk mostly about houses and very typically these start with two wire connections sometimes there’s four. And these are the typical ring wires. So the two wires are tip and ring and this goes all the way back to the days of the little plug the switchboard with Mabel there and identifies a part of the connector so tip and ring are actually the green and red wires and I always remember it as a ring and red both begin with ours.
Now if you have another pair of connectors come in that’s usually a yellow and black pair and the connector is used in almost all of these are gonna be RJ elevens. So we see the phone all the way on the left and that’s our RJ eleven terminated patch cord but that goes usually down in your basement and then eventually winds up connected to the red and green wires going out of your house. And then these flow out into the network and then eventually wind up at the central office or the PBX or private branch exchange. But the thing that we’re going to try and figure out here is how does everybody in the neighborhood do the exact same thing so if we expand this idea here a little bit think about all of the houses in your neighborhood or all of the apartments in your building all of them have analog lines going to them and all of those Tippin ring pairs flow out.
And the first thing that they usually run into is something called an own power distribution frame. So if you’ve seen the closets in the basement of a building or in your friend’s yard a lot of times there’s this panel with all of these wires coming into it. These are just connections. Now this power distribution frame usually feeds a larger cable or 25 pairs of 50 pair sometimes as many as eight hundred pairs leaving your neighborhood. Again there’s no power here. It’s just one wire connected to another wire or a bunch of individual homes being connected out of a larger connection. Now, these eventually run into a power distribution frame and that’s usually your central office or what we call the classified switch now distribution frames and buildings sometimes look like the two on the left here.
We’ve got a big C block and a 66 block. These are also called punched on blocks so you have a punch down tool you take your tip and ring wires and actually pound them into these connectors. And of course, on the right, we have our friends the RJ 45 and the RG eleven. An interesting fun fact about the RG eleven is it fits right into the middle of an RJ forty-five. Remember
That RG 45 has eight wireless
The RJ eleven for the tip and ring wires that red and green pair corresponds to the blue pair on a network that’s wired for data. So the blue pair and this is why we see a lot of blue pair wires in telco closets. They go to pair four and five well we look at this another way. Here
Note that they all have the same area code they have the same prefix where they differ is in that station code they’re all aggregated together in that larger cable and then eventually wind up at that five yes switch or class five switch five ESFS is just one popular chancy and we look end and there are a couple of things that jump out at us the local loops on either end of this where the two telephones are those are both analog but in the middle the PSTN is digital. So what we’re taking is your analog voice. We converted to digital and then we reconverted back to analog at the other end. Well, so how does all that happen. Well we’ve got to add to our diagram here is something called the subscriber line card and the Kodak Kodak is responsible for converting from analog to digital and back again. Now we’re going to talk about codecs later on in another video. But for right now I’ll just tell you that in the publisher’s telephone network that 7-Eleven is the most popular Kodak and gee that 7 Eleven uses a process called pulse code modulation to get this done. And again we’ll we’ll talk about how that works later on.
So you make a phone call it goes out your local loop eventually winds up in your local exchange carrier or central office the subscriber line card that your station is connected to converts your analog to digital using pulse code modulation so that the samples the voice samples are now in digital form and they’re transmitted across the network. And we’re going to talk about it ones as the truck later on until they eventually hit another class five switch central office PBX and then that Kodak takes those digital samples and recreates the analog waveform and then so passes it down the analog local loop and that’s how it works for the mend. Now the individual details will cover as we talk about codecs and GDR 7-Eleven in particular and tea cares things like that. That is the general overview of your local loops operation.
This was traditional telepathy and chapter two in the packet guide to voice over IP. Now as you’re perusing the site and checking out all the other things here sometimes it can get a little overwhelming. But I want you to remember that you can do this. It’s just networking after all so it doesn’t matter who you are. These are just some rules and some ideas get your head wrapped around them and you can build something really cool. So take a whack at it