Chapter 2
Preparing to Install the Cisco Unified IP Phone on Your Network
Phone Power Consumption and Display Brightness
The power consumed by a phone depends on its power configuration. See
configuration overview. See
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
Phone Model
Power Configuration
Cisco Unified
IEEE 802.3af Class 3 power from a Cisco switch, with bidirectional
IP Phone 7975G,
power negotiation enabled
7965G, 7945G
External power
Cisco Unified
IEEE 802.3af Class 3 power from a Cisco switch (with or without
IP Phone
bidirectional power negotiation enabled) or from a third-party
7971G-GE
switch
External power
Cisco Unified
Cisco prestandard PoE from a switch that supports a maximum of 7
IP Phone 7970G
W power per port, with bidirectional power negotiation enabled
Cisco prestandard PoE from a Cisco Switch that supports 7 W or
15.4 W power per port, without bidirectional power negotiation
IEEE 802.3af Class 3 power from a Cisco switch, without
bidirectional power negotiation
IEEE 802.3af Class 3 power from a third-party switch
IEEE 802.3af Class 3 power from a Cisco switch, with bidirectional
power negotiation enabled
Cisco prestandard PoE from a Cisco Switch that supports 15.4 W
power per port, with bidirectional power negotiation enabled
External power
1. Starts at approximately 1/2 brightness, changes to full brightness when the phone negotiates additional power.
When a phone is powered with a method that does not support full brightness for the phone screen, the
Note
phone Brightness control (Settings > User Preferences > Brightness) does not allow you to set the
brightness to the maximum value.
OL-23092-01
Table 2-2
for the maximum power consumed by a phone for each
Cisco Unified IP Phone Administration Guide for Cisco Unified Communications Manager 8.5
Providing Power to the Phone
Table 2-1
for a power
Max. Power
Consumed from a
Phone Screen
Switch
Brightness
12 W
Full
—
Full
15.4 W
Near full
—
Full
6.3 W
Approx. 1/2
6.3 W
Approx. 1/2
6.3 W
Approx. 1/2
6.3 W
Approx. 1/2
1
10.25 W
Full
10.25 W
Full
—
Full
2-5
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