Apple iPhone users may soon be able to make calls without using cell phone minutes as Global IP Solutions announced Monday a software developer's kit that enables voice over IP on Apple's handset.

Developers will be able to use VoiceEngine Mobile to build standalone VoIP applications for Apple's App Store, as well as applications that integrate real-time VoIP communication into iPhone games, chats, social networking, and more.

"The popularity of the iPhone, along with the emergence of various applications and faster connectivity, makes it an ideal platform for developing applications that incorporate quality real-time VoIP, giving consumers real-world communication experiences like in-game, multi-person chat," said Emerick Woods, Global IP Solutions' CEO, in a statement.

Users hoping to utilize the iPhone 3G's high-speed network for VoIP calls are out of luck, as the VoiceEngine Mobile will only work on Wi-Fi hotspots. This is due to Apple's agreement with its exclusive U.S. carrier AT&T to remove applications that violate the mobile operator's terms of services. VoIP calls on a 3G network could potentially eat into AT&T's voice revenue.

This agreement also recently came up when Apple removed a tethering application from its App Store. The application, Netshare, allowed customers to use the phone's 3G data plan on a computer. Although Apple has not confirmed it, it is widely believed that Netshare was pulled because it conflicted with AT&T's terms of service for the handset.

While there have been other VoIP applications for the iPhone from companies like Fring, those often required "jailbreaking" the handset.

Global IP Solutions is also the inventor of the internet Low Bit Rate Codec (iLBC), a narrowband speech algorithm designed to optimize calls made over the Internet.