CPC Main Group
H04M 19/00 Current supply arrangements for telephone systems (for selecting-equipment H04Q1/28)
4 direct subcodes
Child Classifications
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- H04M 19/02 providing ringing current or supervisory tones, e.g. dialling tone or busy tone
- H04M 19/06 in which current supply sources at subordinate switching centres are charged from the main exchange
- H04M 19/08 with current supply sources at the substations (generating ringing current H04M19/04)