Hi there,
There's no CUCM support. Check out the following post: https://supportforums.cisco.com/message/1155145#1155145
Q. What is the Cisco® Unified IP Phone 500 Series?
A. The Cisco Unified IP Phone 500 Series is a group of cost-effective, entry-level phones designed to work ***solely with the Cisco Unified Communications 500 Series for Small Business.
http://www.cisco.com/en/US/prod/collateral/voicesw/ps6788/vcallcon/ps7293/qanda_c67-466070_ps9730_Products_Q_and_A_Item.html
Hardware Features and Enhancements
The Cisco 500 Series phones offer customers the option of having a 10/100 switch port for connecting to a co-located PC via a LAN connection, if needed. The Cisco Unified IP Phones 521SG and 524SG offer the 10/100 switch port, while the 521G and 524G models do not. Orderable now.
***These phones are designed for use with the Cisco Unified Communications 500 Series for Small Business only. They will not work with any other Cisco platform.
http://www.cisco.com/en/US/prod/collateral/voicesw/ps6788/phones/ps9730/prod_bulletin_c25-495153.html
HTH,
Chris