Abstract: In September 2023, Huawei released the world’s first commercial mobile phone supporting two-way satellite communication. The satellite-direct-to-phone has become the focus of global mobile communication. The satellite-direct-to-phone will promote the development of technology and industry for the terrestrial mobile communication system to meet the global seamless coverage, users anytime, anywhere access to the business needs, and further bridge the social digital divide. The satellite-direct-to-phone belongs to the category of mobile satellite service, which needs to adopt the corresponding satellite frequency. The satellite frequency is a scarce space resource. Therefore, the satellite frequency is the one of primary factors to be considered in the development of the satellite-direct-to-phone. This paper starts from the technical route of the satellite-direct-to-phone, firstly expounds the main three technical routes of the international satellite-direct-to-phone system, then analyzes the available frequency of the satellite-direct-to-phone, and finally gives the corresponding development suggestions. This paper is the first time to analyze the technical route and available frequency of China’s satellite-direct-to-phone in detail. According to the development of China, it is proposed to develop satellite-direct-to-phone service in stages. It is suggested to strengthen the satellite network data reservation and technology research of "same frequency of satellite and terrestrial", to lay the foundation for promoting the development of China’s satellite-direct-to-phone service.