IPC Subgroup
H04Q 1/442 with out-of-voice band signalling frequencies
Introduced: January 1980
Last revised: January 2006
Full Title
Details of selecting apparatus or arrangements > Electrical details > Signalling arrangements; Manipulation of signalling currents > using AC > with out-of-voice band signalling frequencies
Classification Context
- Section:
- ELECTRICITY
- Class:
- ELECTRIC COMMUNICATION TECHNIQUE
- Subclass:
- SELECTING