Hi,
Step 1 
While powering up the phone, press and hold #.
Step 2 When the light on the mute button and handset light strip turns off and all other lights (line button, headset button, speakerphone button and select button) stay green, press 123456789*0# in sequence.
When you press 1, the lights on the line buttons turn red. The light on the select button flash when a button is pressed.
If you press the buttons out of sequence, the lights on the line button, headset button, speakerphone button, and select button turn green. You will need to start over and press 123456789*0# in sequence again.
After you press these buttons, the phone goes through the factory reset process.
Do not power down the phone until it completes the factory reset process, and the main screen appears.
Thanks,
Anand
HI Gordon,
This process is described a tad differently in this "older" doc, maybe worth a try;
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 # until 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 take place.
After you press these keys, the line buttons on the phone flash red, and the phone goes through the factory reset process.
Do not power down the phone until it completes the factory reset process, and the main screen appears.
Cheers!
Rob
From the doc you linked;
Step 1 While powering up the phone, press and hold #.
Step 2 When the light on the mute button and handset light strip turns off and all other lights (line button, headset button, speakerphone button and select button) stay green, press 123456789*0# in sequence.
When you press 1, the lights on the line buttons turn red. The light on the select button flash when a button is pressed.
If you press the buttons out of sequence, the lights on the line button, headset button, speakerphone button, and select button turn green. You will need to start over and press 123456789*0# in sequence again.
After you press these buttons, the phone goes through the factory reset process.
Do not power down the phone until it completes the factory reset process, and the main screen appears.
From the doc I linked;
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 # until 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 take place.
After you press these keys, the line buttons on the phone flash red, and the phone goes through the factory reset process.
Do not power down the phone until it completes the factory reset process, and the main screen appears.
They look different to me
Cheers!
Rob
Gordon I was able to do the factory reset on the 6921 by:
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 # until each line button flashes on and off in sequence in amber.
Step 3 Release # and press
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 # until each line button flashes on and off in sequence in amber.
Step 3 Release # and press 1 then press 123456789*0#.
Good Luck,
Zack
