Inline Power: Cisco and 802.3af

Cisco IP phones can be supplied with power in a number of ways, including using

• An external power supply unit (a power “brick”): An external power supply unit provides power directly to a phone from an electrical socket.

• Power over Ethernet (PoE) from a switch: Switches can use PoE to supply power over an Ethernet cable to connected devices such as IP phones.

• A midspan power injector/inline power patch panel: A midspan power injector is a device that sits between a switch and an IP phone and supplies power to the connected phone. An inline power patch panel is a patch panel that sits between a switch and multiple IP phones and supplies power to those phones.

Many Cisco switches can send power over Ethernet cables to connected devices such as Cisco IP phones. There are two methods of supplying PoE: using a Cisco proprietary method and using the IEEE 802.3af standard. Both the Cisco proprietary method and IEEE 802.3af provide power to connected devices over switch port pins 1, 2, 3, and 6.