The telephone network extends worldwide, so you can reach nearly anyone on the planet. When you compare that to the state of the world just years ago, when it might have taken several weeks to get a one-way written message to someone, you realize just how amazing the telephone is!
Surprisingly, a telephone is one of the simplest devices you have in your house. It is so simple because the telephone connection to your house has not changed in nearly a century. If you have an antique phone from the s, you could connect it to the wall jack in your house and it would work fine! In this article, we will look at the telephone device that you have in your house as well as the telephone network it connects to so you can make and receive calls. See the next page to get started.
That's it! You can dial this simple phone by rapidly tapping the hook switch -- all telephone switches still recognize " pulse dialing. The only problem with the phone shown above is that when you talk, you will hear your voice through the speaker. Most people find that annoying, so any "real" phone contains a device called a duplex coil or something functionally equivalent to block the sound of your own voice from reaching your ear. A modern telephone also includes a bell so it can ring and a touch-tone keypad and frequency generator.
A "real" phone looks like this. Still, it's pretty simple. In a modern phone there is an electronic microphone, amplifier and circuit to replace the carbon granules and loading coil. The mechanical bell is often replaced by a speaker and a circuit to generate a pleasant ringing tone.
The telephone network starts in your house. A pair of copper wires runs from a box at the road to a box often called an entrance bridge at your house. From there, the pair of wires is connected to each phone jack in your house usually using red and green wires. If your house has two phone lines, then two separate pairs of copper wires run from the road to your house.
The second pair is usually colored yellow and black inside your house. See What do the little boxes that the phone company has around our neighborhood do? Along the road runs a thick cable packed with or more copper pairs. Depending on where you are located, this thick cable will run directly to the phone company's switch in your area or it will run to a box about the size of a refrigerator that acts as a digital concentrator.
The concentrator digitizes your voice at a sample rate of 8, samples per second and 8-bit resolution see How Analog and Digital Recording Works for information on digitizing sounds. It then combines your voice with dozens of others and sends them all down a single wire usually a coax cable or a fiber-optic cable to the phone company office. Either way, your line connects into a line card at the switch so you can hear the dial tone when you pick up your phone. If you are calling someone connected to the same office, then the switch simply creates a loop between your phone and the phone of the person you called.
If it's a long-distance call, then your voice is digitized and combined with millions of other voices on the long-distance network. Your voice normally travels over a fiber-optic line to the office of the receiving party, but it may also be transmitted by satellite or by microwave towers. See How does a long-distance call work? You know the hand crank on those old-fashioned telephones?
It was used to generate the ring-signal AC wave and sound the bell at the other end! Not only is a telephone a simple device, but the connection between you and the phone company is even simpler. In fact, you can easily create your own intercom system using two telephones, a 9-volt battery or some other simple power supply and a ohm resistor that you can get for a dollar at Radio Shack.
You can wire it up like this:. Your connection to the phone company consists of two copper wires. Usually they are red and green.
The green wire is common, and the red wire supplies your phone with 6 to 12 volts DC at about 30 milliamps. If you think about a simple carbon granule microphone, all it is doing is modulating that current letting more or less current through depending on how the sound waves compress and relax the granules , and the speaker at the other end "plays" that modulated signal.
That's all there is to it! The network is also under immense development with 5G soon entering the market. Sweden is undergoing a change where all old technique in regards to telephony is slowly but steadily being replaced. This entails old copper wires that were used for landline telephony and ADSL broadband for a long time. The technique has been replaced by IP telephony that is managed via fiber optics. Part of the old landline network that is mostly owned by Telia, is being replace by fiber or mobile technology.
This means that Telia is replacing landline telephony with solutions via the mobile network, and broadband via the phone plug ADSL with fiber or mobile broadband. Changing technology is therefore needed and if you want to rely on fast telephony you need to change to IP telephony through your broadband supplier in the future.
Home Glossary Landline phone. Landline phone A landline phone is an apparatus that is connected to the landline network to communicate. Rent a phone? Different types of landline phones Today you can find different types of phone. Decreased use According to statistics the use of landline phones have seen a steady decrease.
From old to new technique Sweden is undergoing a change where all old technique in regards to telephony is slowly but steadily being replaced. Knowledge center. Operating information. Release notes. Remote support. Terms and conditions. Privacy policy. Mobile PBX. How does a landline call from your home or office connect you to the intended recipient? If you think about it, it is pretty amazing that if you want to talk to someone, all you need to do is pick up a very simplistic, readily available device - of which you likely own several - and dial a few short digits.
The connection is virtually instant. Furthermore, this network of telephones extends around the globe, so that pretty much anyone on the planet can be reached as long as they also own a phone and are connected to that network. It wasn't really that long ago that the only way to communicate with someone on the other side of the world was to write a letter - one that might take many weeks to reach its intended recipient. For a land line call to work, the telephone must be connected to wires which then link to the rest of the phone network.
The network itself begins in your own home, where a pair of copper wires for every phone line that you have runs in from a box somewhere at the roadside frequently referred to as the entrance bridge into your house. Those wires go to your phone jacks, to which your telephones are connected. The entrance bridge is connected to a thick cable which runs along your road, and either goes directly to the phone company's switch, or to another, larger box which acts as a digital concentrator.
The digital concentrator is a device which digitizes your voice at an 8-bit resolution and at a rate of 8, samples per second. Your voice is then combined with dozens of other voices which are all sent along one wire often a coax cable or a fiber-optic cable to the phone company's office.
There, your line is connected to a line card at a switch which is what provides you with the dial tone when you pick up your phone. When you call someone local, the switch simply crates a loop between your phone and the telephone of the person you are calling.
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