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.
In order to make phone calls via the Internet one’s device has to be compatible with Softphone software. In example in order to call from a PDA using VoIP technology one has to install Softphone software, in order for it to work properly, PDA has to have Softphone compatibility.