That was not the feature that caught my attention,,, it was the voice scrambling...not sure how that works.
VS is quit simple and is based upon the same technology as PGP from a few years back. A key is needed to decrypt. Good systems have floating freq and scramble technology. Very hard to crack.
I fitted voice scramblers on many tuna boats and base stations. The basic technology breaks voice band energy into 5 audio bands. The filtered energy is passed to a balanced mixer producing upper or lower sideband against the carrier frequency in that band. The USB or LSB is then linearly mixed to one of the other 5 bands. There are about 40,000 combinations. A good scrambler steps through a precisely timed sequence of those combinations. All stations on the same "net" will have the same sequences programmed. All will synchronize to a "master" station at the start of the "net". It was all analog, but pretty effective. The biggest challenge for me was dealing with all the different microphone circuit types. Dynamic, carbon and crystal mikes were a common mix on the boats.