The AIR iPhone is a desktop application created with Adobe AIR and Adobe Flex 3, it simulates the UI of the iPhone. It has the capabilities to make calls, receive calls, check voicemail, add contacts and even send voice messages, all using Ribbit. To use the calling functionality you will need an account with Ribbit, you can get one here Register.
Download - AIR iPhone v3.03
You will also need the Adobe Integrated Runtime if you don’t have it.