GETS isn't the DSN. GETS is basically a way to use the priority bits in a SS7 IAM. DSN, on the other hand, is the modern day AUTOVON. I used to know more about it. All that I remember this late in the night is that there's 2 systems: DSN RED and DSN BLACK. If I remember correctly DSN BLACK is for non-classified communications and DSN RED is for classified communications. For secure communiations they use STU-III phones with some insane key lengths. The key is stored on a paersonal flash memory card that's in the shape of... a key! You plug it into an ITU, turn, and ta-da! That's all that I remember off the top of my head.
