Power Guidelines; Phone Power Consumption And Display Brightness - Cisco 7975G Software Manual

Providing Power to the Phone

Power Guidelines

Table 2-1
Phone 7975G.
Table 2-1 Guidelines for Powering the Cisco Unified IP Phone 7975G
Power Type
External power— Provided
through the CP-PWR-CUBE-3
external power supply
External power—
Provided through the Cisco
Unified IP Phone Power Injector
IEEE 802.3af PoE
power—Provided by a switch
through the Ethernet cable
attached to the phone

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.
Power consumption values shown in the table include power losses in the cable that connects the phone
Note
to the switch.
Table 2-2
Phone Model
Cisco Unified
IP Phone
7975G
Cisco Unified IP Phone 7975G Administration Guide for Cisco Unified Communications Manager 7.0 (SCCP and SIP)
2-4
provides guidelines that apply to external power and to PoE power for the Cisco Unified IP
Guidelines
The Cisco Unified IP Phone Series use the CP-PWR-CUBE-3 power supply.
The Cisco Unified IP Phone Power Injector may be used with any Cisco Unified IP Phone.
Functioning as a midspan device, the injector delivers inline power to the attached phone.
The Cisco Unified IP Phone Power Injector is connected between a switch port and the IP
Phone, and supports a maximum cable length of 100m between the unpowered switch and
the IP Phone.
The Cisco Unified IP Phone 7975G support IEEE 802.3af Class 3 power on signal pairs
•
and spare pairs.
• The Cisco Unified IP Phone 7975G do not support Cisco inline PoE.
• To ensure uninterruptible operation of the phone, make sure that the switch has a
backup power supply.
• Make sure that the CatOS or IOS version running on your switch supports your
intended phone deployment. Refer to the documentation for your switch for operating
system version information.
Table 2-2
Power Consumption and Display Brightness for Power Configurations
Power Configuration
IEEE 802.3af Class 3 power from a Cisco switch, with
bidirectional power negotiation enabled
External power
Chapter 2 Preparing to Install the Cisco Unified IP Phone on Your Network
for the maximum power consumed by a phone for each
Table 2-1 for a power
Max. Power Phone
Consumed Screen
from a Switch Brightness
12 W Full
— Full
OL-15790-01