The Yeastar O2 Module is a telecommunications interface device designed to expand the functionality of compatible Yeastar PBX systems. This module features two FXO ports, allowing connection to traditional analog telephone lines and enabling businesses to integrate existing landline services into modern IP telephony infrastructures. The compact module measures 120 mm in width, 90 mm in depth, and 25 mm in height, weighing approximately 180 g. It supports standard analog line protocols and provides reliable connectivity for voice communication. The O2 Module is designed for stable operation in office environments with operating temperatures between 0 °C and 40 °C, as well as storage temperatures from -20 °C to 70 °C. It requires connection to compatible Yeastar PBX systems for operation and draws power directly from the host device. The module's construction utilizes durable materials with a metal housing to protect against electromagnetic interference and ensure long-term reliability. Installation is straightforward with standard RJ11 connectors for both FXO ports and supports typical analog line parameters, including loop start signaling and DTMF tone detection. This interface allows businesses to maintain existing analog telephone services during the transition to VoIP systems and offers flexibility in telecommunications infrastructure planning. The device supports standard voice compression codecs when used with compatible systems and maintains voice quality through robust signal processing. Each port can handle simultaneous voice channels with clear audio transmission suitable for business communication. The O2 Module represents a practical solution for organizations needing hybrid telephony setups that connect traditional and modern communication technologies.