Cisco Systems OL-23092-01 manual Phone Power Consumption and Display Brightness, Max. Power

Chapter 2 Preparing to Install the Cisco Unified IP Phone on Your Network

Providing Power to the Phone

Phone Power Consumption and Display Brightness

The power consumed by a phone depends on its power configuration. See Table 2-1for a power configuration overview. See Table 2-2for the maximum power consumed by a phone for each configuration option and the correlating phone screen brightness level.

Note Power consumption values shown in the table include power losses in the cable that connects the phone to the switch.

Table 2-2	Power Consumption and Display Brightness for Power Configurations
			Max. Power
			Consumed from a	Phone Screen
Phone Model		Power Configuration	Switch	Brightness
Cisco Unified		IEEE 802.3af Class 3 power from a Cisco switch, with bidirectional	12 W	Full
IP Phone 7975G,		power negotiation enabled
7965G, 7945G
		External power	—	Full
Cisco Unified		IEEE 802.3af Class 3 power from a Cisco switch (with or without	15.4 W	Near full
IP Phone		bidirectional power negotiation enabled) or from a third-party
7971G-GE		switch
		External power	—	Full
Cisco Unified		Cisco prestandard PoE from a switch that supports a maximum of 7	6.3 W	Approx. 1/2
IP Phone 7970G		W power per port, with bidirectional power negotiation enabled
		Cisco prestandard PoE from a Cisco Switch that supports 7 W or	6.3 W	Approx. 1/2
		15.4 W power per port, without bidirectional power negotiation
		IEEE 802.3af Class 3 power from a Cisco switch, without	6.3 W	Approx. 1/2
		bidirectional power negotiation
		IEEE 802.3af Class 3 power from a third-party switch	6.3 W	Approx. 1/2
		IEEE 802.3af Class 3 power from a Cisco switch, with bidirectional	10.25 W	Full1
		power negotiation enabled
		Cisco prestandard PoE from a Cisco Switch that supports 15.4 W	10.25 W	Full
		power per port, with bidirectional power negotiation enabled
		External power	—	Full

1. Starts at approximately 1/2 brightness, changes to full brightness when the phone negotiates additional power.

Note When a phone is powered with a method that does not support full brightness for the phone screen, the phone Brightness control (Settings > User Preferences > Brightness) does not allow you to set the brightness to the maximum value.

Cisco Unified IP Phone Administration Guide for Cisco Unified Communications Manager 8.5

OL-23092-01 2-5