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How Does VOIP Work?
How Does VoIP Work?
Getting into a highly technical discussion about the in’s and out’s of VOIP would be easy to accomplish, but the fact is that most people wouldn’t care. They’re simply impressed that it does work and don’t want too much more for information. For those who do want to know how it works, a basic overview of the methods used will be more helpful than the specifications and technicalities.
Basic Concepts
Every one of us has quite likely used a computer with a microphone. We have recorded voices or sounds to use as ringtones, or to send to relatives or for some other purpose.
When we do this, what’s involved is that the computer is recording in just tiny pieces of the overall sound or sentence. Every bit is just a minute, compressed amount of the whole.
When you play it back again the computer takes that batch of small sound bytes, decompresses them and then puts them back together so that you or your recipient can hear what you recorded.
Voip or Voice Over Internet Protocol is the same concept. The difference is that the small sound pieces aren’t stored on your computer, but instead are sent over an Internet Protocol network and are played for the person on the other end all within seconds or a fraction of. Of course, that’s a highly simplified explanation and there is a good bit more that’s necessary to make it work.
Audio Compression
Compression of the audio bits are needed in order to send them in a timely way. Just like compressing files on your computer, or compressing your stuff in your suitcase, compression helps to make the whole package smaller and easier to send. There are multiple ways to compress audio files.
Codecs
You’re probably familiar with some of the codecs that can be used just by using your computer. Regardless of whether it is an MP3, an AVI,or a DVD, you need a codec, or a means to decompress it to play it. To play anything your computer needs to understand the compressor or decompressor that was used in order to compress or decompress in the same way. The algorithms that are used to address this need are known as codec’s.
Different codecs are used for decompressing or compressing various types of information, such as movies or music.
VOIP uses codecs that are ideal for compressing human voices. What that accomplishes is that the amount of bandwidth that it would ordinarily take to send a stream of audio that was not compressed is reduced to a fraction of what it was. This reduces the time and cost to send the information.
Packet Sending
When you speak into your VOIP device, the sound gets recorded by the computer, it is then compressed to a small percentage of what it was, placed into chunks of data which are called packets, and then sent over the network to the person on the other end.
To understand what a packet actually is and does, Vint Cerf, who is lauded as the “Father of the Internet” explained it in a very simplistic way that works well to address it here.
He said that a packet was nothing more than an internet postcard. To send just a small amount of information would take only one postcard, but that if you wanted to send an entire letter, it would require the use of many postcards to get all the information written down. There was also the chance that the postman or the postal office might lose one of the postcards so that all of them were not delivered.
Then too, is the need to put all the postcards back together in the right order so that the message makes sense. That involved marking each postcard, or in this case, each packet, so that there was some way to know their logical order.
Like letters in the mail or Vint Cerf’s postcard analogy, some of the packets of IP data will be lost to us over the transport through the network. The Codec will need to find a way to fill in the missing blanks in a way that people can understand. Known as PLC or packet loss concealment, the packets may be sent several times each to allow for the loss,or another means, called Forward error correction may also be used to provide for your smooth transfer of voice to the person you’re phoning.
Summarizing It All
To make a long story short, information is broken down, recorded, reassembled and sent as packets through the wire to the person on the other side. Video as well as audio may be sent in this fashion.
There is of course a great deal more to VOIP than just the sending and receiving of the information or packets through the internet. There have to be protocols or languages if you will, that allow for computers to find each other, as well as a format or means of sending the information that the computers or networks agree on.The way that the information will be sent between the two devices that need to communicate needs to be the same.
VOIP is today used in a wide variety of different devices such as IP Telephony, ATA’s, as well as many others. More traditional phones can be used with adaptors to permit communication over a VOIP network.
VOIP telephony is far more cheap than traditional telephone service in most cases and requires an outlay of about the same amount of money as you might pay for a telephone installation to aquire the necessary equipment for your service.
Typical VOIP telephone service today costs about 35 dollars per month for virtually unlimited national and international service. Installation costs and equipment in most cases are under 100 dollars.
This entry was posted on Saturday, December 12th, 2009 at 9:47 am and is filed under Internet, Phones. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
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