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Cisco Unified IP Phone 6921, 6941, and 6961 Administration Guide for Cisco Unified Communications Manager 7.1 (SCCP)
OL-19025-01
Chapter 9 Troubleshooting and Maintenance
Monitoring the Voice Quality of Calls
Performing a Factory Reset
When you perform a factory reset of the Cisco Unified IP Phone, the following information is erased or
reset to its default value:
• User configuration settings—Reset to default values
• Network configuration settings—Reset to default values
• Call histories—Erased
• Locale information—Reset to default values
• Phone application—Erased (phone recovers by using the image in the inactive partition of flash to
boot up).
Before you perform a factory reset, ensure that the following conditions are met:
• The phone must be on a DHCP-enabled network.
• A valid TFTP server must be set in DHCP option 150 or option 66 on the DHCP server.
To perform a factory reset of a phone, perform the following steps:
Procedure
Step 1 Unplug the power cable from the phone and then plug it back in.
The phone begins its power-up cycle.
Step 2 While the phone is powering up, and before the Speaker button flashes on and off,
press and hold #.
Continue to hold # u
ntil each line button flashes on and off in sequence in amber.
Step 3 Release # and press 123456789*0#.
You can press a key twice in a row, but if you press the keys out of sequence, the factory reset will not
ta
ke place.
After you press these keys, the line buttons on the phone flash red, and the phone goes through the
factor
y reset process.
Do not power down the phone until it completes the factor
y reset process, and the main screen appears.
Monitoring the Voice Quality of Calls
To measure the voice quality of calls that are sent and received within the network, Cisco Unified IP
Phones use these statistical metrics that are based on concealment events. The DSP plays concealment
frames to mask frame loss in the voice packet stream.
• Concealment Ratio metrics—Show the ratio of concealment frames over total speech frames. An
interval conceal ratio is calculated every 3 seconds.
• Concealed Second metrics—Show the number of seconds in which the DSP plays concealment
frames due to lost frames. A severely “concealed second” is a second in which the DSP plays more
than five percent concealment frames.