Power over Ethernet

From VoIP.ms Wiki

Power over Ethernet (PoE) is a standard which allows both DC power and wired network data to be carried to a device over the same wiring. It is most commonly used to power desktop IP Phones in an office environment, although some other hardware (such as wireless access points and security cameras) also makes use of the standard.

The power is normally inserted using either a PoE-enabled local area network hub or by a small device packaged specifically as a PoE power inserter.

See How to Troubleshoot PoE Issues In Your VoIP Phone System.