Power Outage - Cisco 7821 Administration Manual

When you install a phone that is powered with external power, connect the power supply to the phone
Note
and to a power outlet before you connect the Ethernet cable to the phone. When you remove a phone that
is powered with external power, disconnect the Ethernet cable from the phone before you disconnect the
power supply.
The following table provides guidelines for Cisco IP Phone 7821, 7841, and 7861 power.
Table 4: Guidelines for Cisco IP Phone 7821, 7841, and 7861 power
Power type
External power: Provided
through the
CP-PWR-CUBE-3=
external power supply
External power—Provided
through the Cisco IP Phone
Power Injector.
PoE power—Provided by
a switch through the
Ethernet cable attached to
the phone.

Power Outage

Power outages and other devices can affect your Cisco IP Phone.
Your access to emergency service through the phone requires that the phone receive power. If a power
interruption occurs, Service and Emergency Calling Service dialing will not function until power is restored.
In case of a power failure or disruption, you may need to reset or reconfigure the equipment before you can
use the Service or Emergency Calling Service dialing.
Power Reduction
You can reduce the amount of energy that the Cisco IP Phone consumes by using Power Save or EnergyWise
(Power Save Plus) mode.
Cisco IP Phone 7821, 7841, and 7861 Administration Guide for Cisco Unified Communications Manager 10.0 (SIP)
Guidelines
The Cisco IP Phone 7821, 7841, and 7861 uses the CP-PWR-CUBE-3 power
supply.
The Cisco IP Phone Power Injector may be used with any Cisco IP Phone.
Functioning as a midspan device, the injector delivers inline power to the
attached phone. The Cisco IP Phone Power Injector connects between a
switch port and the IP Phone, and supports a maximum cable length of 100m
between the unpowered switch and the IP phone.
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 that runs on your switch supports
your intended phone deployment. See the documentation for your switch
for operating system version information.
Phone Power Requirements
7