Using Voice over Internet Protocol (VoIP) calling applications on your mobile phone can save you money if you make a lot of international calls or travel out of the country often. iPhone users have several options when deciding what app to download.
IDC projected over 9 billion minutes of voice traffic to travel over worldwide packet networks in 2000, exceeding 135 billion minutes in 2004. Service revenue is projected at 1.6 billion in 2000 and 18.7 billion in 2004.