According to the current situation of optical fiber communication, the SAT-5B portable optical telephone is developed using internationally advanced technology with the features of small and handy structure, portability, full duplex communication (SAT-5B with three-way calling), high speech quality, large dynamic range, and easy operation, and is widely used in the construction and maintenance of optical cable, optical fiber communication, and optical fiber CATV, etc., and especially suitable for communication under severe atmospheric condition.