It is a type of communication between two or more people who share computer data in real time. The data can include screen, documents, graphics, drawings and applications that can be manipulated by participants.
Concerning practical implementation, the VoIP gateways have proven to be the best. Many companies are successfully using the IP telephony thanks to its two main characteristics
Decrease in international and long distance call cost expenditures
Stable communications between company’s offices throughout different cities and counties