Cisco 8821 Manual page 19

Call State
On Call
Idle
There are many factors that can influence actual battery life time.
Usage
Battery life will be reduced when the Cisco Wireless IP Phone 8821 or 8821-EX user is on call, using Bluetooth, using
applications, receiving XSI messages, or navigating the menus on the phone.
Coverage
Ensure the Cisco Wireless IP Phone 8821 and 8821-EX remain in a good RF coverage area and is able to maintain a constant
connection to the Cisco Unified Communications Manager.
If the Cisco Wireless IP Phone 8821 or 8821-EX user travels out of range and remains out of range for a significant duration,
battery life can be reduced.
Scan Mode
The Cisco Wireless IP Phone 8821 and 8821-EX supports 3 different scan modes (Continuous, Auto, Single AP), where
Continuous is the default configuration.
The configured scan mode will determine the battery life baseline.
•
Continuous scan mode is designed for Cisco Wireless IP Phone 8821 and 8821-EX users that are constantly on the
move where frequent roaming events occur and to maximize performance and connectivity, but power consumption is
higher.
•
Auto scan mode is designed for Cisco Wireless IP Phone 8821 and 8821-EX users that roam occasionally and require
more idle battery life than Continuous scan mode can offer.
•
Single AP scan mode is designed for Cisco Wireless IP Phone 8821 and 8821-EX users that do not roam and require
maximum idle battery life.
Proxy ARP
For optimal idle battery life, it is recommended to utilize an access point that supports the Cisco Compatible Extensions (CCX)
Proxy ARP feature. CCX Proxy ARP allows the Cisco Wireless IP Phone 8821 and 8821-EX to remain in suspend mode
longer versus having to wake up at each DTIM period, therefore reducing power consumption.
The Cisco Lightweight Access Points and Cisco Autonomous Access Points support CCX Proxy ARP, but Cisco Meraki
Access Points do not.
For Cisco Lightweight Access Points, CCX Proxy ARP is enabled by default and non-configurable. For Cisco Autonomous
Access Points, CCX Proxy ARP is disabled by default, but can be enabled via the dot11 arp-cache optional command.
If the access point does not support CCX Proxy ARP, then the Cisco Wireless IP Phone 8821 and 8821-EX must wake up at
each DTIM period, which can reduce idle battery life as much as 50%.
Transmit Power
Cisco Wireless IP Phone 8821 and 8821-EX Wireless LAN Deployment Guide
Scan Mode
Battery Time
Continuous Up to 13 hours
Auto Up to 13 hours
Continuous Up to 48 hours
Auto Up to 96 hours
Expected
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