In 1987, AT&T advertised its new secure telephone that operated according to the STU-III standard of the NSA. Interestingly enough, it seems that this phone was never produced, and several years later, AT&T came up with a completely different model.
Advertisement for an STU-III secure telephone made by AT&T (1987)
The STU-III standard
STU-III stands for Secure Telephone Unit - Third Generation and was a standard from the NSA for secure telephone equipment capable of encrypting voice calls (and data) up to the highest classification level.
The STU-III standard was developed from 1985 to 1986 by NSA in cooperation with the Government Electronics Group (GEG) of Motorola. In 1986, three companies were selected for the production of telephone sets based upon this standard: Motorola, RCA and AT&T.
Under the new standard, they could manufacture devices not much larger than a common desktop telephone set, where previous voice encryption systems, like the STU-I, required equipment as large as a small fridge. The best known STU-III became the version manufactured by Motorola:
Motorola's STU-III secure telephone (photo: Crypto Museum)
The STU-III made by AT&T
Despite all the ambitious claims in the advertisement of 1987, it would take another 5 years before AT&T's STU-III phone would become available for government and commercial customers. Interestingly enough, this phone had a completely different design than the one in the advertisement, as can be seen in this picture:
AT&T's STU-III secure telephone (photo: Crypto Museum)
This new design was similar to AT&T's common series of desktop phones, later known als the Lucent MLX-series and used in offices all over the world (see photo below). Big difference is that the STU-III version was larger and much heavier as its bottom part was made of die-cast aluminium in order to shield most of the electronic components.
Common AT&T/Lucent/Avaya MLX office phone
The STU-III made by RCA
Somewhat surprisingly, the phone in the AT&T advertisement from 1987 looks much more like the STU-III phone that was manufactured by RCA, an American electronics company that was founded in 1919 as Radio Corporation of America. RCA's STU-III unit was the largest of the three versions (measuring ca. 34 x 31 x 13 cm), but also the one that was least commonly used.
RCA's STU-III secure telephone (photo: Crypto Museum)
A close look shows that the arrangement of the buttons on RCA's STU-III phone is a bit different from those in the AT&T advertisement, but the general design and button layout is much closer than the eventual unit sold by AT&T.
Probably the phone shown in the advertisement was just a prototype or an artist's impression and for some reason or another, AT&T decided to manufacture a device using the parts of its regular office phone family.
Maybe some readers of this blog can provide more information about this issue.
Links and sources
- Crypto Museum: STU III Third generation secure telephone unit
- Web page by Jerry Proc: STU III (Secure Telephone and KSD-64)
- Granite Island Group: Secure Communications Systems