Patent classifications
H
ELECTRICITY
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H04
ELECTRIC COMMUNICATION TECHNIQUE
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H04M
TELEPHONIC COMMUNICATION
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1/00
Substation equipment, e.g. for use by subscribers
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H04M1/66
with means for preventing unauthorised or fraudulent calling
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H04M1/667
Preventing unauthorised calls from a telephone set
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H04M1/675
the user being required to insert a coded card, e.g. a smart card carrying an integrated circuit chip
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