The Cisco Unified IP Phone 6921 is now obsolete (past End-of-Life and End-of-Support status).
End-of-Sale Date: 2014-07-30
End-of-Support Date: 2019-07-31
Cisco's End-of-Life Policy
You can view a listing of available Cisco Unified IP Phone 6900 Series offerings that best meet your specific needs
If you want support information for the Cisco Unified IP Phone 6921 documentation, it may be available through Cisco.com Search or in the Cisco Community