The energy required to communicate comes only from the sound of the user. Acoustic energy is converted into electricity and then from electrical to acoustic. All of our voice-operated phones are made of polymer alloy which provides excellent chemical resistance, high impact resistance, non-flammability and stability to ultraviolet light. Such telephones are used in situations where security is critical in communication, such as in combat systems on military ships. Our sound-powered telephone systems are MIL-STD compliant.