Secure Voice Telephone Systems: How the Department of Defense Can Save Millions (Unclassified Digest of a Classified Report)

A narrowband secure voice technique is planned to protect civil agencies' telephone conversations from being monitored or intercepted by unintended listeners. The Department of Defense (DOD) selected a wideband secure voice technique to protect its own nontactical telephone conversations. This was done so that the same wideband technique could be used for communicating between nontactical and tactical secure voice systems. Generally, narrowband systems require more complex terminals needing more space and power and are more costly than wideband terminals. Conversely, wideband systems generally require more costly transmission facilities.