However, when Vocaltec made it happen in 1996, a lot of jaws dropped. By using their own Internet phone software, Vocaltec has made possible a call to be established between PC to PC. Still, the quality of the voice left much to be desired.
What! Me worry about quality!
What would you do when you want to go for a holiday? Pack your luggage of course! So you start throwing in your toiletries, your clothing and many other personnel stuff. Before you know it, you realise that you have packed too much stuff into your luggage. Well, it's either you repack your stuff or start trying to squeeze as much as you can into your luggage.
The same thing can be said for transmission of voice via IP. To receive a VoIP call with the quality of the voice comparable to that of a typical telephone call, you would need a data transmission speed of 64kb/s. Now, there is no way of dedicating such a large bandwidth on a data network for voice. Therefore, there has to be some form of compression taking place which would squeeze the voice data into a considerable size prior sending it over a packet switching network.
Other than the bandwidth issue, there is a time delay issue as well. Time is needed to compress voice data, transmit and then decompress it, process and finally making it audible to the receiving party. All this streaming would result in a delay of a few hundred milliseconds. In other words, both callers may not be able to speak at the same time.
Delay will also result in jitter as well. That is to say, when a voice data packet does not arrive in time at the end of a gateway while a voice streaming is taking place, the packet will be dropped and will not be recovered. This will cause the receiver to hear jittering of speech from the caller.
With the realisation of VoIP, voice and data will be carried over a single network. In such a multi service environment, data traffic can be highly unpredictable and because each business organisation tends to load their network to the maximum, packet loss is inevitable .
The scenario above has caused much headache for the research folks. On one hand, they have a technology that brings great promises but on the other hand, it poses many barriers against having wide acceptance of the new technology.
And since then, the world has seen a huge advancement in Internet telephony technology. Voice specification (H.323) has been endorsed by the International Telecommunication Union (ITU), many companies have developed Internet telephony software , VoIP vendors have been busy researching and coming out with voice gateways, Internet phones, and other IP telephony hardware.
