Voice-over-Internet protocol is a protocol optimized for the transmission of voice through the Internet or other packet-switched networks. VoIP is often used abstractly to refer to the actual transmission of voice (rather than the protocol implementing it). This latter concept is also referred to as IP telephony, Internet telephony, voice over broadband, broadband telephony, and broadband phone.
Use an iPhone? Here are some options you can check out if you want to save some money on international calls..
sipgate.com
sipgate brings VoIP to your iPhone. Finally. You can use sipgate to place and receive calls over Wi-Fi using any SIP-based VoIP-service.
iCall
iCall VoIP on the Apple iPhone from Arlo & Andy on Vimeo.
