Developer group Fring has updated its application to allow users with jail-broken iPhone 4 handsets to make video calls over 3G and to Android and Symbian devices.
A video clip on the Fring blog shows a video call to a non-Apple phone and, although the quality does not appear to be the best, it does work.
Fring acknowledged that performance over 3G is subject to the mobile operator's 3G coverage and quality.
The app supports multi-tasking, so it can run in the background and alert users to new video calls, voice calls or chat without having to open it.
A social stream presents a chronological list of all tweets, Facebook updates, chats and calls in one place, according to Fring, and an address book manages buddy lists and merges contacts.
The app is the first of its kind to take on Apple's official FaceTime video calling software, which is restricted to Wi-Fi and iPhone 4 to iPhone 4.
The move by Fring could encourage Apple to make FaceTime available over 3G sooner rather than later.
An Adobe Flash substitute dubbed Frash, meanwhile, has been created by a developer to work on the iPad, bypassing the ban imposed by Apple.
However, experts have warned that users thinking about jail-breaking their iPhones risk downloading malicious applications in the future.
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