Preventing the dialling or sending of predetermined telephone numbers or selected types of telephone numbers, e.g. long distance numbers

Full Title

Substation equipment, e.g. for use by subscribers > with means for preventing unauthorised or fraudulent calling > Preventing the dialling or sending of predetermined telephone numbers or selected types of telephone numbers, e.g. long distance numbers

Classification Context

Section:

ELECTRICITY

Class:

ELECTRIC COMMUNICATION TECHNIQUE

Subclass:

TELEPHONIC COMMUNICATION