Researchers claim 400,000 iPhones are already running on the China Mobile network - even though the product hasn't officially shipped into the country yet.

Marking the popularity of the Apple phone, which has seen over a million of the devices unlocked for use in other countries and on other networks, researchers at In-Stat report the figure, citing China Mobile for the claim.

"The figure surprised us as it is fourfold of that we estimated before," the firm said. "We have never doubted that the iPhone will achieve greater success than the iPod in China if Apple teams with China Mobile to launch its Chinese version," In-Stat said.

In-Stat believes that the smartphone is evolving into a increasingly wide range of mobile devices, where cellular voice communications are just one function of the converged appliance.

Apple hasn't yet announced a network partner for the introduction of iPhone in China, with the company recently confirming a single meeting with China Mobile to discuss the proposition.

The company will likely do well with its iPhone in China, where users are prepared to pay more for their mobile and tend to use their phones for accessing entertainment and personal content, as well as for day-to-day business use, the report explains.