A random acoustic phase scrambler device is installed in-line with a telecommunications fiber link to prevent voice detection via fiber links. The device includes a transducer to produce vibrations; a length of optical fiber positioned to receive the vibration from the transducer; and a random acoustic phase driver configured to control the intensity and frequency of the vibrations. The transducer produces randomized vibrations within an acoustic bandwidth. The device is configured to introduce device-induced phase changes to signals within the telecommunications fiber link. The bandwidth of the device-induced phase changes is greater than the bandwidth of voice-induced phase changes, and the device-induced phase changes are greater in intensity than the voice-induced phase changes. The device-induced phase changes mask voice-induced phase changes through the telecommunications fiber link that are otherwise detectable by voice detection equipment tapped to the telecommunications fiber link.