Internet telephony or VoIP is a technology, allowing carrying a voice /telephone/ thanks to IN TERNET infrastructure.

The beginning is not so far in the past – 1995 and the company represented it is VocalTec.

Year later in 1996 Vocaltec announces that will develop with other companies hardware allowing audio connections between internet telephone and regular phone. They called this hardware Voice Gateway.

DESCRIPTION OF VoIP Technology

When analog voice from the phone reaches the Voice Gateway it first digitalize it and compress it into standard data blocks, also known as IP packets. These IP packets are send to internet to another Voice Gateway where the process is reversed. Using this technology, 3 different types of calls are possible:

1. PC to PC

2. PC to Phone

3. Phone to Phone /or also known as callback/

There are several protocols to carrying voice. The most popular are SIP, H323, IAX.

For voice compression are using codecs as G729, G723, G711 and G726.

CALLBACK service

In order to use a callback service, a subscriber, which must first be dialed in order to trigger a return call. On hearing a ringing tone, the subscriber simply hangs up and awaits the callback. On receiving this, usually within a few seconds, the customer picks up the phone and dials the required number.

The cost of making a telephone call via callback consists of two parts, as the caller is paying for an outbound and inbound call at the same time.

For example, if a customer from Germany is calling a phone number in Japan, and it costs 8 cents per minute to phone Germany (the callback, which is an incoming call) and 20 cents per minute to phone Japan (the destination call, which is an outgoing call), then the caller will pay a total of 28 US cents a minute.

This may still be less expensive than calling directly from Germany to Japan, which is primarily why callbacks are used – to make Cheap Phone Call s.

Callback is often automated through the use of web callback or mobile phone applications by companies such as Wwcallback.com, offering cheap phone calls at all.

Web callback is very easy way to make calls without using expensive hardware or complicated software and can be used by everyone.

No need of special technical skills or high speed internet are required – just a simple registration in telecoms sites like Wwcallback.com.

The main advantage is that you don’t need any special software, hardware – all you need is mobile or land line phone.

PC to PC

PC to PC service requires a special voip software to be installed on your computer. This software also requires some settings that must be provided from the ITSP /internet telephony service provider/. You will need also an broadband internet access, microphone and headphones.

All this makes it a little difficult, but effective. There are free networks offering this service like skype, but as a free service the quality often is poor. This service is offering for free by the operators.

PC to Phone

It is the same as PC to PC service but instead dialing another PC you dial a regular mobile or land line number.

Again you will need special voip software, headset, microphone and broadband internet access. The advantages are that you will save money, but with unknown providers often the quality is very poor.

By: Ivan Iliev

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