What Is VoIP?

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Many have heard of the VoIP phone service, but are unsure what the term VoIP stand for. VoIP stands for Voice Over Internet Protocol. “Great, but what does that mean and how does it affect me?” I can hear you say. I though the same when I first heard the term.

In simple terms what the VoIP service does is to convert an analogue audio signal into a digital audio signal that can be transferred over the internet. In order to understand how this works and why it is necessary, you first need to understand how the internet transfers files. In order for a file to be transferred over the internet from one computer to another, the signal has to be cut down into small pieces, called ‘packets’. This can only be done if the information being cut up is in binary format, i.e. in the form of a stream of 1s and 0, such as 11000010. very basically, such a stream of binary digits can be cut into small packets such as 1100 and 0010 , sent over the internet, then put back into order when received to read 11000010. As I said, this is a simple example, purely to give a rough idea of how a VoIP phone service sends the data throughout the internet. In practice the VoIP data streams are very much larger as are the packets.

Since the VoIP information has to be in binary form, the signal, of course, has to be a digital one. The digital signal is ‘packetized’ then the packets sent over the internet. The way this is done is to send the signals from one computer to another until it reaches the destination computer, rather like cell phone signals are sent from one antenna to another till they reach the one nearest to you, then from there to your mobile phone receiver.

In fact the packets will take the quickest route through the internet which can sometimes cause problems in that they may arrive at the receiving end in a different order to that in which they were sent. Some may even be lost, or ‘dropped’, leading to a less than perfect signal. The VoIP receiver must therefore be equipped with the means to put them back in the right order and compensate for ‘dropped’ packets.

The digital information is then converted back to an analogue signal so that it can be detected by the human ear. Normal digital phones can work this way, but the VoIP service uses the internet rather than conventional telephone system.

It is easy to see the potential benefits of this type of telephone system. It should be completely free of charge, other than the cost of the internet connection, since there are no wires or dedicated transmission and reception equipment required. The voice signals are sent as easily as you would send email. In fact VoIP services can completely change the way in which we make phone calls; as revolutionary as the change to mobile cell phones, and many phone companies are wakening up to this and are now selling complete VoIP phone systems for residential users and global corporate companies.

How do you make a phone call using a VoIP service? There are a number of ways:

1. The easiest way is from one computer to another. All you need is the software required to convert, packetize, transmit and receive the signal, a microphone and speakers. Once connected your only cost is the normal payment to your internet provider such as AOL or whichever you use. There is no regular payment for the VoIP service itself other than the initial software.

2. You can use an analogue telephone adapter (ATA). You plug your normal telephone into the ATA, also called a ‘Gateway’, then connect the ATA to your internet connection. When make a phone call, the ATA changes the analogue voice signal into a digital one, packetizes it and you can then send it on its way along the fastest route each packet can find to the destination computer.

3. The third way is use an IP phone which looks just like a normal handset. They contain all the software necessary to make a call and plug directly into an RJ 45 Ethernet connector on your computer. This type of VoIP service is popular with medium to large companies operating VoIP networks.

One thing you will need for an efficient VoIP service is a fast internet connection such as cable or broadband. An old modem connection won’t be much good for VoIP. You can also take your VoIP phone with you, much as you do with your mobile. With most VoIP service providers, however, you can get free calls and the phone is, in effect, your home telephone with your home telephone number. It’s just like carrying your home phone around with you.

Many companies operate a VoIP service on their internal networks, and calls between users on the network are free. Thus the Hong Kong office could call the London office completely free of charge.


The features available with VoIP services generally come free with the system and include useful features such as call waiting: you will be informed that another caller is waiting for you to finish the call you are on, conference calling, caller ID by number and name, call transfer: you can transfer calls to another phone or even to your mobile, repeat dialing, auto dialing, etc. Many of these are normally chargeable with ordinary phone services, but are generally free with the VoIP service.

These are just a few of the many different services available with VoIP phone systems. If you intend to purchase one for yourself or your company you should make a list of what services you require, which are essential and which are ‘nice to have’ then call in an expert to make the recommendation. You may be able to use some of your existing hardware if you are currently operating a digital phone system, as most medium to large company telephone systems are these days. This doesn’t apply to residential users who just need an interface between their phone and internet connection as already described.

I have often been asked if the person you are calling has to have a VoIP service. The answer is no, but if you are calling from an ordinary phone to VoIP or using a VoIP service to call an ordinary phone, call charges will normally apply whereas FROM VoIP service TO VoIP service, they normally do not.
Peter Nisbet is an industrial chemist with a great interest in internet file transmission and reception systems and runs many websites including http://www.data-voip-solutions.com where many aspects of VoIP services and systems are discussed.

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