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← Siemens Phone
Telephone voice encryptor
Data Security Module (DSM) Voice is a digital encryptor for
analogue telephone lines,
developed around 1996 by Siemens
in Munich (Germany).
The DSM Voice is connected between the regular analogue telephone set
and the analogue network (POTS).
It uses a smart card for authentication.
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The unit is normally placed aside or under the telephone set.
At the rear
are sockets for the phone, the line and the
external power supply unit (PSU).
The control panel consists of an LCD display,
3 LEDs and a single push-button.
The slot above the display accepts a smart card, as shown here.
It is used for authentication and public key exchange (PKE).
Insert the card and press the button on the control panel,
to enter secure mode (crypto).
Call partner authentication is performed automatically,
and for each call, a new session key will be generated by the device.
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MRCELP vocoder technology is used to provide good quality speech in
encrypted mode.
The DSM Voice is only suitable for speech (voice) at it uses a lossy
compression technique. Alternative DSM units
were available for other types of data, such as DSM Fax,
DSM X.25,
DSM Link
and DSM ISDN
[2].
At present, no further information about these units is available.
If you know more about the Siemens DSM family of devices,
or if you happen to have user manuals, please let us know.
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The following DSM family members are known:
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- DSM Voice
- DSM Fax
- DSM X.25
- DSM Link
- DSM ISDN
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ISDN
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Integrated Services Digital Network
Digital telephone standard that was intended to replace the analogue
POTS system, but that has since been superceeded by IP-telephony.
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MRCELP
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Modified Residual Code Exited Linear Prediction
High-quality low-bitrate speech digitiser, used for encrypted voice
connections over regluar analogue lines. Improved variant of MELP
and MELPe, that produces better results at 9600 baud.
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POTS
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Plain Old Telephone System
Old analogue telephone system.
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© Crypto Museum. Created: Wednesday 06 February 2013. Last changed: Friday, 18 January 2019 - 20:14 CET.
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