The VPBX Extension Devices (VEDs) are minimal POTS interfaces that may be placed anywhere on the HPNA network. Calls are placed from the VEDs through the VPBX Home Gateway Unit (VHGU) to external parties as appropriate for the type of call. The VED design consists of:
- One HPNA port (provides connectivity to VHGU)
- One FXS port (provides BORSCHT functions to external telephone)
- Power fail relay to connect the local phone to the Central Office line
- Device power over unused yellow/black wire pair or via external power supply with power selection logic to use the local wall adapter if present
The VED may be powered from either an external power supply or from power provided by the VHGU over an unused yellow/black wire pair. When power is available, an LED will indicate power and the VED FXS port will contact the VHGU via the HPNA interface. Should power be unavailable to the device, the LED will indicate power loss and a relay will open connecting the VED FXS port directly to the Central Office RJ-11. A block diagram of the VED is provided in Figure 1.