(Reuters) - China Mobile (0941.HK), the world's largest mobile carrier by subscribers, has 10 million iPhone users even though it does not yet have an agreement with iPhone maker Apple (AAPL.O), its chairman told Reuters on Monday.

Wang Jianzhou also said Apple had promised to make an iPhone compatible with China Mobile's TD-LTE standard when its next-generation model comes out. He could not say when this would happen.

"We have not yet got agreement with Apple," Wang said on the fringes of the ITU World telecoms fair in Geneva. "Apple promised to provide, when they develop the iPhone for LTE, that it will include TD-LTE. We are discussing the details."

China Mobile has previously said it had met several times with Steve Jobs, Apple's co-founder and former chief executive who died this month, to discuss introducing an iPhone based on its own home-grown network standard.

The company is developing its next-generation TD-LTE mobile network technology, and Wang said there should be commercial trials next year in some cities.

China Mobile had more than 630 million customers at the end of September. But many are lower-end users who only make calls and send text messages.

China's three carriers have been plagued by falling average revenue per user as they offer subsidized handsets from Samsung (005930.KS) and HTC (2498.TW) for multi-year contracts to attract smartphone users to more expensive services.

In more developed markets, the iPhone spurred consumers to make far greater use of lucrative data services when it was launched four years ago, thanks to its ease of use and well-supplied App Store of games and other applications.

In China, only China Unicom (0762.HK)(CHU.N) has the iPhone so far.

However, Wang said China Mobile was already benefiting to some extent from the iPhone, thanks to Apple's network of stores in the country.

"The total number of iPhones in China Mobile's network has reached 10 million -- and we didn't pay any subsidies," he said.