What is Power Feed or Phantom Power?
Power Feed is used to supply approximately 40VDC 1W to BRI devices such as ISDN Phones which do not have their own power supply. ISDN devices with their own power supply normally do not require Power Feed. There are three types of Power Feed: PS1/Phantom. -40VDC 1W across pairs 3/6 and 4/5 PS2. -40VDC 8W uses wire pair 7/8 PS3. -40VDC 8W uses wire pair 7/8 (Non-ETSI) Patapsco Liberator devices support the more common PS1/Phantom Power Feed. This feature is a hardware add-on which must be purchased with Liberator devices at the time of ordering. An external 100-240VAC to -40VDC power supply, which must be connected to Liberator as well as the usual mains connection is supplied with the unit. Liberator devices can be purchased with Power Feed fitted for ports in blocks of four, and Power Feed can be enabled and disabled on a per-BRI port basis.
