What is VoIP?
VoIP stands for Voice over Internet Protocol.
As the term says VoIP is the transmission of voice communication through IP packets and, therefore, through the Internet. VoIP can use accelerating hardware to achieve this purpose and can also be used in a PC environment.
Webopedia defines it as: A category of hardware and software that enables people to use the Internet as the transmission medium for telephone calls. For users who have free, or fixed-price Internet access, Internet telephony software essentially provides free telephone calls anywhere in the world. To date, however, Internet telephony does not offer the same quality of telephone service as direct telephone connections.
There are many Internet telephony applications available. Some, like CoolTalk and NetMeeting, come bundled with popular Web browsers. Others are stand-alone products. Internet telephony products are sometimes called IP telephony, Voice over the Internet (VOI) or Voice over IP (VOIP) products.
How does VoIP work?
Early on it was determined that it was possible to send a voice signal to a remote destination digitally, as well as via analog. To do that, we have to digitize it with an ADC (analog to digital converter), transmit it, and at the end transform it again in analog format with DAC (digital to analog converter) to use it.
This is basically the way VoIP works, sending voice information in digital form in discrete packets rather than in the traditional circuit-committed protocols of the public switched telephone network (PSTN). A major advantage of VoIP and Internet telephony is that it avoids the tolls charged by ordinary telephone service.
What are the advantages?
When you are using Public Switched Telephone (PSTN) line, you typically pay for the time you use: The more time you stay on the phone the more you’ll pay. And you generally don’t have the option of talking with more than one person at a time (or you can, but at increased cost).
With VoIP, you can talk all the time with any person you want (the requirement is that the other person has an internet connection), with no regard to distance, and you can talk with many people at the same time.
Not convinced? Consider that, at the same time, you can exchange data with people are you talking with, sending images, graphs and videos.
Why isn’t everybody using it?
Like many new technologies, there have been some problems with VoIP. In order to be effective, voice data communication has to be a real time stream. (You wouldn’t want to finish a sentence, then wait for many seconds before you could hear the other side answering.)
With normal internet protocols, you can have a network consisting of many routers (20 – 30 or more) which can result in a very high round trip time (RTT).
In addition to standard IP, VoIP uses the real-time protocol (RTP) to help ensure that packets get delivered in a timely way. Using public networks, it is currently difficult to guarantee Quality of Service (QoS). Better service is possible with private networks managed by an enterprise or by an Internet telephony service provider (ITSP).
As of this writing, VoIP is still plagued by lack of generally accepted interoperability standards.
VoIP FAQ Source DSLReports.com
