The Yeastar TA400 is a standalone FXS VoIP gateway designed to connect traditional phones, fax machines, and PBX systems to IP telephony networks and IP-based PBX systems. It features four FXS ports that ensure compatibility with analog legacy devices and integrate them into modern IP infrastructures. This gateway supports SIP and IAX2 protocols, offers flexible call rules, and provides interoperability with a variety of softswitches, PBX systems, and IP-PBX platforms such as Elastix and Lync Server. With carrier-grade reliability, it is built on advanced hardware and software architecture for stable performance in small and medium-sized businesses. The web-based configuration interface simplifies setup and reduces effort and time for deployment. Key features include cost-effective communication solutions, robust feature sets for diverse requirements, and seamless integration into existing systems without extensive technical knowledge. The TA400 measures approximately 21.5 cm in width, 12.5 cm in depth, and 4.3 cm in height, weighing around 0.9 kg, making it compact for various installation environments. It operates efficiently within a standard temperature range of 0 °C to 40 °C, ensuring durability under typical office conditions. This model is the successor to earlier versions of the TA series and focuses on improved interoperability and user-friendliness for businesses transitioning from traditional to IP-based telephony.