Understanding Basic Voice Over IP
VoIP or Voice over IP is a telephone/Internet technology whereby people can make phone calls, but they do so without using the traditional Bell Public System Telephone Network. Instead users make calls over the Internet. The phone numbers still exist, but the calls are transmitted using Internet technologies. The main difference between VoIP and a Bell system call is the VoIP is digital, the Bell system is analog.
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A Successful VoIP Telephone Call
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A successful telephone call uses a digital signal, not an analog one like the Bell phone systems. The voice is sampled. This is taking random pieces of the voice signal to determine if the quality is good or not. If it is good, the voice signal is quantized, meaning that special algorithms are applied to turn the voice signal into digital. Finally, the packet is encoded; this means that the digital packet is put it into a form that can be placed on the Internet. At the receiving end the reverse occurs.
The Mechanisms Needed to Make a Successful VoIP Phone Call
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Mechanisms Since the technology that is used is digital, there are different technologies that are used to make the VoIP call.rnrnThe phones are different. They may look like ordinary phones but they must have special software and hardware that turns the voice signal into the digital format.rnrnThere must also be phone technology that can be used to connect the calls over the Internet. These are gateways and call managers.rnrnFinally, there are technologies called FX0(Foreign eXchange Office) and FXS (Foreign eXchange Subscriber) which will allow an analog phone call to be placed to an VoIP receiver, and a VoIP call placed to a Bell system phone.
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Circuits and Packets
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Telephone Circuit A traditional phone call occurs when a phone number connects to another phone number. A circuit is established from one end to another, part by part, no matter how near or far, like a roadway. The circuit is open as long as both phones are in service and connected to each other.rnrnIn VoIP there is no circuit. The packets travel to their destination but can take different routes. The packets are small but individual. When the packets are put together at the receiving end the voice is heard.
Frequencies
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Packet Frequency Voice sampling takes place at the outset of a phone call. This is necessary in order to provide a complete reconstitution of the voice. The voice is sampled by a frequency. This allows a voice to be reproduced at the receiving end. A frequency is like a wave with high points and low points. However, they can be reproduced exactly.
Quality of Service
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Quality of Service Since a digital signal is a piece by piece signal, there are several problems that can occur as it is transmitted. The bandwidth that is used could become congested. The packets may be dropped resulting in the breakup of the signal and the phone call. Packet signals may travel at different speeds causing distortion of the phone call.rnrnAddressing these problems come under the heading of quality of service. There are different technologies to make the packet signal as uniform as possible.
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References
- Photo Credit mta cable mode image by IKO from Fotolia.com telephone display image by AGITA LEIMANE from Fotolia.com mechanism image by Adrian Hillman from Fotolia.com circuit image by amlet from Fotolia.com The indicator of the musical equipment. image by Andrey Khritin from Fotolia.com Seal crown with laurel leaves image by patrimonio designs from Fotolia.com
