Subscriber circuit
The subscriber circuit an analog or digital central office or PBX provides for the connection of analog phones the link between the terminal, usually the phone, and the actual switching equipment represents.
The main functions of the subscriber circuit can be represented by the BORSCHT formula :
- B attery feed
- DC power supply to the end device
- O vervoltage protection
- Overvoltage protection
- R inging
- Calling the desired terminal
- S ignalling
- Loop monitoring, recording of the signaling
- C Oding
- A / D and D / A conversion ( coding ) of the voice signals, mostly using PCM (only in digital switching technology)
- H YBRID
- Two-wire to four-wire conversion ( hybrid connection ) and termination of the subscriber connection line
- T esting
- Connection option for testing subscriber line and terminal device