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Chapter 2 Preparing to Install the Cisco Unified IP Phone on Your Network
Providing Power to the Phone
2-6
Cisco Unified IP Phone Administration Guide for Cisco Unified CallManager 5.0 (SCCP), Cisco Unified IP Phones
OL-8148-01
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) will not allow you to set the brightness to the maximum value.
Table 2-2 Power Consumption and Display Brightness for Power Configurations
Phone Model Power Configuration
Max. Power
Consumed
from a Switch
Phone
Screen
Brightness
Cisco Unified
IP Phone
7970G
Cisco prestandard PoE from a switch that supports a
maximum of 7 W power per port, with bidirectional
power negotiation enabled
6.3 W Approx. 1/2
Cisco prestandard PoE from a Cisco Switch that
supports 7 W or 15.4 W power per port, without
bidirectional power negotiation
6.3 W Approx. 1/2
IEEE 802.3af Class 3 power from a Cisco switch,
without bidirectional power negotiation
6.3 W Approx. 1/2
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 power negotiation enabled
10.25 W Full
1
1. Starts at approximately 1/2 brightness, changes to full brightness when the phone negotiates additional power.
Cisco prestandard PoE from a Cisco Switch that
supports 15.4 W power per port, with bidirectional
power negotiation enabled
10.25 W Full
External power — Full
Cisco Unified
IP Phone
7971G-GE
IEEE 802.3af Class 3 power from a Cisco switch (with
or without bidirectional power negotiation enabled) or
from a third-party switch
15.4 W Near full
External power — Full