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← Telsey Phone
Digitally encrypted telephone
The Cryptophone 7000 was a secure telephone
for use on analogue networks
(POTS), with fully digital encryption and decription of speech and fax data.
It was developed and manufactured in 1990 by Telsy in
Turin (Italy) as the succesor to the successful 1st generation
KV-3000 series.
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The Cryptophone 7000 was an all-in-one solution and was only slightly
bigger than a standard telephone set. It came in a black or white case,
and had an extremely clear and intuitive user interface with 12 push-buttons
and a crisp 2 x 40 character LCD display.
The image on the right shows a typical Telsy Cryptophone 7000 with its
handset on-hook. The display
shows the name of the phone, plus the current
date and time. A small physical key
to the left of the push-buttons
is used to select the required mode of operation:
crypto or clear.
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The 2nd generation Cryptophone 7000, features Digital Signal Processing (DSP)
technology and hardware-based encryption. It was successfully sold to the
Government and Corporate sectors, but was also sold as an OEM product
by various ICT Security suppliers, including
Thomson (now: Thales)
[5] and Racal.
The Cryptophone 7000 was in production
for many years, until is was succeeded in 2005 by the 3rd generation
Cryptophone T3 was still available
from Telsy in 2012.
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Operating the Telsy Cryptophone 7000 is extremely easy and intuitive.
All user I/O is via the keyboard and the LCD-screen. Voice communication
is possible via the handset, or hands-free via the built-in speaker (top)
and microphone (front).
The unit can hold up to 16 different cryptographic keys, each of which is
identified by a label (i.e. a name) for authentication.
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The small key, to the left of the keyboard, is used to select the operating
mode. It has three positions (from left to right):
- L: Setup
- M: Operation (normal)
- R: Locked (incoming calls only)
The cryptographic keys can be entered in Setup-mode, using the SET-KEY
function. Each key consists of 16 digits (0-9) plus an optional label,
consisting of up to 8 alphanumerical characters. From this the phone
calculates an identifier.
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Once the cryptographic keys have been programmed, all the user needs to do
is dial the other party, talk in clear, and then press the CR-button.
The Cryptophone 7000 at both ends will then synchronize and look for a common
key (i.e. a key that is known by both parties). If such a key is found
(i.e. the identifier matches),
both phones switch to secure mode (CRYPTO).
If no common key is found, a dialogue appears on the LCD-screen to indicate
that a RANDOM CRYPTO KEY will be used instead. Such a random key is only
valid for a single session and cannot be intercepted by a third party.
In this mode, authentication of the other party is not possible.
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Full-duplex and half-duplex
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By default, the Cryptophone 7000 works in full-duplex mode, which means that
the user can speak and listen at the same time. Under certain circumstances,
e.g. when the line is too bad, the unit can switch to half-duplex, which means
that only one partly can speak at a time. This is also the case when the
Cryptophone 7000 is used over a satellite link.
In half-duplex mode, the change-over of direction (i.e. the transmitting
party) is voice-controlled (VOX). In noisy environments however, the #-key
(bottom right of the keyboard) can be used to switch to manual operation.
In this case the #-key is used as the Push-To-Talk switch (PTT).
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The interior of the Cryptophone 7000 can easily be accessed by removing six
bolts from the bottom of the unit.
The top half of the case can then be removed and
the interior becomes visible.
At the left is the telephone interface
with a Siemens PSB4506 speech circuit
[3].
The keyboard is mounted on a separate board that is held in place by 6 small
plastic snaps. It can easily be removed and folded aside, so that the
digital circuitry becomes visible.
The PCB is very well designed with a good eye for detail and
Electro-Magnetic Compatibility (EMC).
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In fact, the design is much better than, for example, the
US CVAS-III crypto phone of the same era.
The Cryptophohe 7000 has a professional quality PCB with
sufficient ground planes.
At the left are two AT&T T-7522 codecs
that are used for full-duplex speech encoding and decoding.
At the right is the microprocessor
with its EPROM and other peripheral chips, shown above.
At the heart of the digital circuit are two Texas Instruments
TMS-320 Digital Signal Processors
[4], of which the leftmost one is an EPROM-version.
All programmable and critical ICs are in sockets and can easily be swapped.
The firmware of the Cryptophone 7000 was updated several times.
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© Crypto Museum. Created: Thursday 03 May 2012. Last changed: Thursday, 14 December 2023 - 09:12 CET.
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