STU-II

The STU- II was developed by the National Security Agency telephone for secure conversations. It provides up to six users to use encrypted communication via time-sharing. The phone was manufactured by ITT Defense Communications, Nutley, New Jersey. An OEM partner was the Northern Telecom.

According to information from the National Cryptologic Museum of the NSA from 2005 is the phone since the 1980s still in use today. It uses the Linear Predictive Coding algorithm LPC -10 at 2.4 kbit / s to digitize language and the Key Distribution Center (KDC ) for the key management. The NSA was also known that the STU- II B is the standard for secure telephone narrowband calls.

The STU- II replaced the phones STU -I, KY -3 and Navajo I. The latter was a secure telephone in a briefcase, which were of 110 units built in the 1980s for use by senior government officials. The Navaho I also took LPC 10th

A total of some 10 000 STU- II were produced.