A hacker claims to have managed to get an iPhone to engage in true VoIP calls.

The Unofficial Apple Weblog (TUAW) reports that hackers eok and Samuel have managed to get VoIP calls working using Session Initiation Protocol (SIP).

The solution isn't perfect as yet, but they have managed to get SIP registration and "signalization" working, the report claims. When the work is complete, users will be able to make voice calls over WiFi using the solution.

The developers have now managed to send and receive calls, and are calling out to others to help realise the project.