Twitter allows your friends to answer the question “what are you doing”. This iPhone app concept helps to answer this same question to those who can't reach you on your mobile. Instead of the dial tone, the person hears your short voice message. The prototype is made using Adobe Fireworks.
This video and the app are in Russian only (sorry for that), but there are English subtitles:
About the Project
This concept is one of the developments of the R&D division of the Bercut, where I worked as the head of the usability department.