SMARTONE Mobile Communications is negotiating with Chinese authorities to allow its subscribers to receive and send messages between Hongkong and the mainland. It is expected that such a service will begin at the end of this year in Guangdong. SmarTone is the first company to use a GSM (Global System for Mobile Communications) digital network. The introduction of this system in China will make it possible for the company's mobile phone users to dial the territory from the mainland and vice versa. ''A wireless system is a more economical and quicker way of achieving penetration. Once the . . . arrangement is established, there is no need for subscribers to open an account with the authorities in China,'' said Mr Douglas Li, chief executive officerof SmarTone. The company would not need any syndicated loans within the next three years to cover the project's capital expenditure as it has secured a $700 million loan arrangement with a bank, which it declined to name. The same bank has agreed to underwrite facilities whose maturity date extends beyond 1997. Additionally, Mr Li explained that the existing shareholders' fund together with the normal cash-flow would provide the finances to cover its expected spending. Closer home, the company is also negotiating with Hongkong Telecom CSL for laying the telecommunications network on the local Mass Transit Railway (MTR) system.