What is VoWiFi ? VoWiFi is a Wi-Fi based VoIP service. Where VoIP consists of the hardware and software that enables people to use the Internet as the transmission medium for telephone calls, VoWiFi is the wireless version of this technology which is designed to work on wireless devices such as a laptop, smart phone and PDAs. Nowaday, many cellular phone has WiFi enable features which is mainly created to support VoWiFi applications. VoWiFi promises to be the ideal application to drive both VoIP and broadband adoption forward.
So How this VoWiFi system works ? Basic component for the overall system is wireless network infrastructure, PABX/PBX and SIP server. SIP server is the main component of an IP PBX, dealing with the setup of all SIP calls in the network. A SIP server is also referred to as a SIP Proxy or a Registrar. This SIP server is used to integrate internet swithing system and traditional phone switcing system PBX. SIP can also be used for "traditional telephony", i.e. voice with 3 kHz bandwidth and common number dialing, over IP networks. For this application, the SIP standard is taking over from H.323, which is a protocol from the standardisation organisation of the telecom world, the ITU-T.
How it can be free ? Many organization which already have internet infrastructure and PBX telephone system require to install SIP server. If they want to offers ubiquitous communication, they have to install a few access point that enable roaming and support better voice quality of service (QoS). Next set is configure for system intergration to enable the SIP become a voice gateway for voice traffic. Every single within the organization considered a local call and using the local infrastructure. It is considered free because you're only running the voice application on top of your local internet infrastructure. I can imagine by next 1 to 2 years, we can search in the internet for an open source SIP server configuration or we can freely download the SIP server script for personal usage. Future application probably can determine the MAC address of the device talk each other as set by the SIP server. We can customize the our own SIP server for personal usage. I'm sure that one day, we can have our virtual telco in our house. Our future SIP server can act as a traditional PBX and we can set our local extention number based on the unlimited IPv6 series. Goshhh.... it is possible to have a free phone call in the future dude !