Reduced Phone Charges
Internet telephony is a fast-growing area. Assuming two computers have the same software, then it is possible to make a phone call from one to the other; all you need is a microphone and a headset or speakers. The call travels through the internet system just like any other kind of internet traffic, so the phone company networks are kept out of the loop and, as a result, it's free.
It is also possible to call normal telephones. The call is still treated as internet traffic until it connects with a local exchange, when it becomes an ordinary phone call - and all you pay is the cost of a local call.
At TeamInteract, we use the internet to make many of our phone calls, even though we work at five different locations and talk to lots of suppliers, our telephone bills are kept low.
Using the internet to make conference calls means we avoid the costs of using a more traditional 0870-type, dial-in service. At around 10p/min per caller there, its just no comparison to the free service available over the internet.
There are a number of free entry level telephone systems such as Skype, which takes a minute to download, a minute to set up, and costs nothing. Other, more sophisticated and better quality systems are also widely available.
More information - http://www.telecomsadvice.org.uk/infosheets/voip_voice_over_internet_protocol_and_internet_telephony.htm