Voip

9 Pages 2181 Words

ustomed to from the Public Switched Telephone Network
(PSTN).
Now let's take a walk on the more detailed side of what VoIP is and how it works. First
and foremost, VoIP is an emerging technology still in the early stages. A personal
computer (PC) must capture an analog voice and convert it to a digital signal, compress
the audio with a compression-decompression (codec) device and then move it into the IP
protocol stack. The codecs are at the heart of any IP telephony software. It is an
algorithm that transforms analogue signals into digital ones and vice versa. The next
step is to access the network, which is the premise modem connected to the PSTN and
channeled to the Internet Service Provider (ISP) modem. The next link in the chain of
events is the IP network itself or the Internet. The current structure of the Internet
can make it an unstable and unpredictable carrier. Finally, the voice packet must
transition back from the IP network to the PSTN, to the receivers' modem for conversion
back into analog. Each of these steps adds more delay to the voice packets. A delay
approximately of over 550 milliseconds, which is 400 msecs over the QoS acceptable limit,
is found to occur. These delays and other issues are just some of the challenges facing
the future of VoIP.
WHY IS VoIP AN ISSUE?
Between 1994 and 1997 ISP revenue grew from about $189 million to over $4.75 billion
dollars, making it the telecommunications success story of the nineties. This
extraordinary growth, coupled with relatively inexpensive connectivity for the typical
user has helped drive the emergence of VoIP. To the typical personal user, this
technology will mean nothing more than the ability to make "free" long distance phone
calls. However, to the business world, this technology holds some very profound promises.
It's the ability to avoid long distance phone charges that has many scrambling to control
the future of VoIP. Companies ranging f...