Click for homepage
Motorola
USA
Phone
SECTEL
  
← 3500
  
SECTEL 9600
Secure voice/data terminal · Type 4

SECTEL 9600 is a secure telephone introduced around 1990 by Motorola in Seguin (Texas, USA). It uses Motorola's proprietary Digital Voice International (DVI) encryption algorithm, which offers a reasonable level of security [2]. It is classified as an NSA Type 4 product, which means it can be used for non-sensitive unclassified information — typically business applications. The device was freely available to US businesses as a COTS product. Note that it is not STU-III compatible.

It offers two methods for key management: manual mode, in which keys are generated by the system itself, and automatic public key (APK) which offers a 'keyless' RSA-based technology for exchanging the keys [1].

The SECTEL 9600 is capable of sending voice and data simultaneously at different speeds, depending on the quality of the (analog) telephone line. A series of advanced speech processing algorithms (LPC-10e, CELP and MRELP) have been implemented to ensure superior voice quality at different baud rates [A].
  
Typical view of the Motorola SECTEL 9600 (STU-III)

The SECTEL 9600 was introduced by Motorola around 1990 as a spin-off of the highly successful STU-III telephones (SECTEL 1500 and SECTEL 2500) that were developed for the US Goverment. As the SECTEL 9600 is an NSA Type 4 device, it could be purchased by virtually any business in the US without obtaining an ITAR licence. However, due to the relatively high price (US$ 4495) and the expected limited security of the DVI algorithm, it never met the anticipated popularity.

PLEASE HELP — Although all STU-III telephones have now been discontinued and the SECTEL unit itself is not classified, it is very difficult to obtain information about this unit. Any information, such as the user manual, is most welcome. If you can help us in any way, please contact us.
Typical view of the Motorola SECTEL 9600 (STU-III)
Close-up of the keyboard showing the SECURE and CLEAR keys at the top left.
The ZEROIZE key hidden behind a plastic cap at the rear of the phone.
Close-up of the ZEROIZE key
Warning on the font panel
Power supply unit
Standard power cable
A
×
A
1 / 7
Typical view of the Motorola SECTEL 9600 (STU-III)
A
2 / 7
Close-up of the keyboard showing the SECURE and CLEAR keys at the top left.
A
3 / 7
The ZEROIZE key hidden behind a plastic cap at the rear of the phone.
A
4 / 7
Close-up of the ZEROIZE key
A
5 / 7
Warning on the font panel
A
6 / 7
Power supply unit
A
7 / 7
Standard power cable

Vocoders
At 2400 baud, the SECTEL 9600 uses a 2.4 kbps Linear Predictive Coding algorithm known as Enhanced LPC-10. It is based on the FS-1015 or STANAG-4198 standard that is also used with the Philips PNVX crypto phone. It is suitable for both half and full duplex.

At 4800 baud, Code-Exited Linear Predictive Coding or CELP is used in full-duplex, providing better audio quality. At the highest speed, 9600 baud, an even better algorithm, called Modified Residual Exited Linear Predictive Coding or MRELP, is used in full duplex.

The SECTEL 9600 has a built-in V.24/V.32 modem that can also be used for computer data at baud rates ranging from 75 to 9600 baud. It is tested and compliant with most telephone systems around the world. If the quality of the (foreign) telephone line is below average, the system gracefully degrades to a lower speed, but maintains its Type 4 security.

Other models
To suit both the safety requirements of the customers and US Government regulations, different SECTEL models were manufactured, all based on the same basic hardware design and enclosure. The firmware and the cryptographic algorithms are different however. The diagram below shows how they are positioned. Only the SECTEL 1000 series and 2000 series are STU-III compatible.

SECTEL 9600 SECTEL 2500 SECTEL 1500 SECTEL 3500

Click any of the balloons above for additional information about the related SECTEL model. The SECTEL 9600 is not compatible with any of the other SECTEL models. It can only be used in combination with other SECTEL 9600 units.


Prices
Below are the list prices of the various models [1]. From this list it becomes clear that a higher price does not mean better security. On the contrary: the SECTEL 9600 is the least secure product, which is more than twice the price of the most secure device — the SECTEL 1500.

  • SECTEL 1500, Type 1, sold for US$ 1800
  • SECTEL 2500, Type 2, sold for US$ 2145
  • SECTEL 3500, Type 3, sold for US$ 3395
  • SECTEL 9600, Type 4, sold for US$ 4495
Connections
The SECTEL 1500 phone is powered by an external Power Supply Unit (PSU) that provides three different voltages: +5V (1.75 A), +12V (250 mA) and -12V (210 mA). The PSU is connected to the 7-pin (or 8-pin) 270° DIN socket at the rear of the unit. The socket has the following pinout:

  1. +12V
  2. -12V
  3. +5V
  4. 0V (GND)
  5. 0V (GND)
  6. +5V
  7. 0V (GND)
Documentation
  1. SECTEL 9600 brochure
    Motorola, Inc. 1970.
References
  1. Robert Crotinger, Motorola STU-III Fact Sheet
    Undated.

  2. Motorola SECTEL 9600 features and specifications
    Website (undated).
Further information
Any links shown in red are currently unavailable. If you like the information on this website, why not make a donation?
Crypto Museum. Created: Sunday 11 July 2010. Last changed: Monday, 16 January 2023 - 08:49 CET.
Click for homepage