Houay is an iPhone application which enables access to any VoIP/SIP service like IP PBX'es or VoIP service providers. The application operates only via the WiFi network with iPhone 3G, iPhone 3GS and iPod devices. Features: incoming and outgoing calls, hold and mute , DTMF , call transfer , contact integration. You can change the SIP server (SIP registrar/SIP proxy) in the "Settings" menu of your iPhone or iPod touch. Houay has been tested with with many different solutions.