The Network Telephone Optical Transceiver is a compact device designed to transmit multiple traditional telephone lines and Ethernet data over a single optical fiber. Its key functionality lies in converting electrical signals from telephones and network equipment into optical signals, enabling reliable, long-distance communication of up to 20 kilometers. Major features include support for standard PSTN telephony, high-quality PCM voice coding, and robust immunity to electromagnetic interference. This system is ideally applied for extending corporate phone networks between buildings, connecting remote offices, and integrating communication services in security and surveillance systems, providing a cost-effective and future-proof infrastructure solution.