VOIP - using the internet to make calls

One of the ways in which the internet is changing the world, is by enabling phone calls to be made over the web. Some solutions only allow calls to be made from computer to computer (like the MSN messanger) but others also allow (for a fee of course) calls to regular phone numbers anywhere in the world for very cheap prices. I personnaly like the SKYPE software and use it on a daily basis to communicate with my friends all over the world. the technology that enables these calls is named VOIP or voice over IP and allows to translate our voices into digital packets that can be sent over the internet and then translated back into voice.
In the past year, several companies in the USA (such as vonage) started offering VOIP based telephones for home use. By providing a VOIP phone adaptor, these companies allow you to use you high speed internet connection to call and recieve calls all over the world for a significantly reduced price compared to the old-school telephony companies. A friend of mine who travels all over the world also mentioned that he takes the VOIP phone adaptor with him wherever he goes and connects it to the internet to recieve calls just as if he were at his office and not somewhere else.