with means for preventing unauthorised or fraudulent calling (verifying user identity or authority in secret or secure digital communications H04L9/32)

Full Title

Substation equipment, e.g. for use by subscribers (subscriber services or facilities provided at exchanges H04M3/00; prepayment telephone coin boxes H04M17/00; current supply arrangements H04M19/08) > with means for preventing unauthorised or fraudulent calling (verifying user identity or authority in secret or secure digital communications H04L9/32)

Child Classifications

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• H04M 1/663 Preventing unauthorised calls to a telephone set
• H04M 1/667 Preventing unauthorised calls from a telephone set (H04M1/677 takes precedence)
• H04M 1/677 Preventing the dialling or sending of predetermined telephone numbers or selected types of telephone numbers, e.g. long distance numbers