Phone Power Consumption And Display Brightness; Power Outage - Cisco 7971G-GE - IP Phone VoIP Administration Manual

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 IP Cisco prestandard PoE from a switch that supports a maximum of 7
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
Cisco Unified IP IEEE 802.3af Class 3 power from a Cisco switch (with or without
Phone 7971G-GE bidirectional power negotiation enabled) or from a third-party
switch
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.

Power Outage

Your accessibility to emergency service through the phone is dependent on the phone being powered. If
there is an interruption in the power supply, Service and Emergency Calling Service dialing will not
function until power is restored. In the case of a power failure or disruption, you may need to reset or
reconfigure equipment before using the Service or Emergency Calling Service dialing.
OL-15299-01
Table 2-2
Cisco Unified IP Phone 7970G/7971G-GE Administration Guide for Cisco Unified Communications Manager 7.0
for the maximum power consumed by a phone for each
Providing Power to the Phone
Table 2-1 for a power
Max. Power
Consumed from a Phone Screen
Switch Brightness
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
15.4 W Near full
— Full
2-5