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Publication of FR893632ApublicationCriticalpatent/FR893632A/fr
H04M1/00—Substation equipment, e.g. for use by subscribers
H04M1/66—Substation equipment, e.g. for use by subscribers with means for preventing unauthorised or fraudulent calling
H04M1/667—Preventing unauthorised calls from a telephone set
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Computer Security & Cryptography
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Signal Processing
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FR893632D1943-04-291943-04-29Appareil rendant impossible la composition d'un numéro d'appel sur un cadran de téléphone automatique
ExpiredFR893632A
(fr)