In my collection I have :
TextTell - 1983 - Encrypted Text Transmission via Acoustic Coupler to Telephone mouthpiece ( for Transmission ) and Telephone receiver ( for Reception )
Forbidden by the (then West) German BKA for showing at CeBIT 1983 fair at Hannover
Photos on
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Hope that someone can inform me on which algorithm and which keylenght was used on these units.
T.I.A.
Nap van Zuuren - Gent - Belgium snipped-for-privacy@pandora.be