by generating or selecting signals other than trains of pulses of similar shape, or signals other than currents of one or more different frequencies, e.g. generation of DC signals of alternating polarity, coded pulses or impedance dialling

Full Title

Substation equipment, e.g. for use by subscribers > Devices for calling a subscriber > by generating or selecting signals other than trains of pulses of similar shape, or signals other than currents of one or more different frequencies, e.g. generation of DC signals of alternating polarity, coded pulses or impedance dialling

Classification Context

Section:

ELECTRICITY

Class:

ELECTRIC COMMUNICATION TECHNIQUE

Subclass:

TELEPHONIC COMMUNICATION