VoIP is technology that allows high speed internet lines to be transmit telephone voice data. The study of what VoIP is and how it works begins by looking at the analog telephone and how that transmits voice data along standard telephone line channels.
In its simplest sense,
VoIP, or voice over IP, or voice over Internet protocol, is making telephone calls using an existing internet connection, whether it be broadband or dial-up. The technology works like a digital telephone. Before a digital telephone is explained, however, it is important to discuss how a regular analog telephone works.
An analog telephone is built upon the same idea as a microphone. In both technologies, a sensitive membrane vibrates when exposed to sound (which is really vibrations in the air). When this membrane vibrates, an acoustic-to-electric transducer converts the sound into an electrical current. Most microphones today are dynamic, which means that the transducer functions of the principles of electro-magnetism. The functioning of the transducer is simple, but elegant: as a coil moves around a permanently placed magnet and through its electromagnetic field, it creates varying levels of energy, which is the basis of the electronic transmission that the microphone produces. This electronic translation of sound is then passed down through a wire to a recorder, and amplifier, or a speaker, depending on the purpose of the sound recording.
An analog telephone works on much the same principle. When you speak into the receiver, the sound is translated into electronic signals by the method above. It is then transmitted through phone wires until it reaches the other party, which then hears it through a speaker embedded in the handset. This allows a conversation it take places two ways, as each handset is capable of receiving and transmitting.
VoIP works much the same way, but in a digital context. The difference between digital and electronic is simple, by often muddled, considering the two overlap frequently. An electronic signal is a signal that uses varying pulses of electricity with different wavelengths and amplitudes to carry a message, and is encoded and decoded on each end of the transmission process. In digital technology, instead of using an electric pulse, the transmission is based on binary code (0s and 1s), which is encoded on the first end and second end if it needs to be readable by a human. If not, the transmission can be kept in digital form, which will then be used to talk to programs or other inter computer components.
Just as an analog telephone converts your speech into an electronic signal, a VoIP telephone or a computer functioning as a VoIP telephone through a service like Skype converts your voice into digital "packets." Packets are the building blocks of data transferred through the internet, and are the most basic packages of swapped data. Once your voice is encoded and bundled into packets, it is sent across the web to the party on the other end, where it is unpacked, decoded, and turned back into sound for your partner to hear.
Though this difference is fundamental, it is easy to overlook how important it is. Because VoIP uses existing, newer wires built to transfer huge amounts of data, the sound quality is much higher, and it can offer more services for much less money than a traditional phone company, which is tied up with older, copper wiring and a fee structure that can''t begin to compete with VoIP services. Many VoIP providers sell packages that already include inexpensive long distance calling. This is possible because of the already international reach of the Internet and relative lack of barriers compared to traditional telephone networks.
Because of the way the Internet is structured and agreements already in place between service providers, there is no need for an Internet user in North America to pay access fees in order to view websites in England, for example. Because it uses the Internet, VoIP users in one nation are able to communicate with VoIP users in another nation in much the same way. With a traditional phone, this is not the case because a telecom company must temporarily rent the wires it uses to make a long distance call through an agreement with the carrier. Of course, this is passed on to consumers in the form of high bills and low call quality.
In terms of connecting you to the person you want to talk to, VoIP is also different in many respects. Again, it will be useful to see how an analog telephone works before we discuss it digital version.
With analog telephone service, everyone''s phone is connected using copper wires that plug into the base of a handset, which are a speaker as well as a receiver. When you want to make a call, you pick up the handset, which puts the phone into a state called "off-hook," and connects the speaker and microphone, and activates other auditory equipment. Once the phone is in the "off-hook" state this connected circuitry creates a low-impedance signal of about 300 ohms which is sent to the relay. The relay sends back the dial-tone as a signal that it is ready for you to place a call.
On a modern push-button phone, you dial the numbers corresponding to your desired party. This sends sounds unique to each number to the relay, which recognizes these sounds as the appropriate numbers. The relay then makes a connection between the calling and called party, sending a higher voltage signal down the line to make the other parties phone ring, provided the called party is not "busy" or active. When the called party picks up, the connection is completed and the two parties may speak through their respective microphones.
When the called party is outside of the local exchange, the signal must be carried through what are called "trunk lines." Because these lines do not necessarily belong to the telephone company, they must be leased, and the cost is passed down to the consumer. This is why long-distance calls are more expensive than local calls, and why the connection time may take longer.
As you can see, the telephone network of POTS (plain old telephone service) operates elusively on sounds created by the handset, as well as using electrical current to create sound. A VoIP telephone, obviously, connects on a different system, using packet-switching technology. Because VoIP or internet telephony is a new technology that is displacing an existing technology, it is classed as a disruptive technology, disturbing the order of things and the way that they used to be under the rule of the old technology.
A VoIP connection is made using internet protocol instead of analog telephone protocol. In this process, a connection is created over the internet, which can be seen as a very large telephone network. Once this connection is established through different IP address, which are connected to phone numbers that can be reached by normal phones or usernames that can be reached only by web users, the call is made using digital conversion of sound into binary code, and then into packets.
