IPC Subgroup
H04M 19/04 the ringing-current being generated at the substations
Introduced: September 1968
Last revised: January 2006
Full Title
Current supply arrangements for telephone systems > providing ringing current or supervisory tones, e.g. dialling tone or busy tone > the ringing-current being generated at the substations
Classification Context
- Section:
- ELECTRICITY
- Class:
- ELECTRIC COMMUNICATION TECHNIQUE
- Subclass:
- TELEPHONIC COMMUNICATION