When using Cisco IP Communicator with the UCCX deployment there have been issues caused by changes of the preferences with the option 'Optimize for low bandwidth'.
Performing that change may drop calls or the call recording feature not to work, so I found defect CSCug29122 in order to hardcode the settings to avoid that users 'play' around with the settings.
Bug ID: CSCug29122
Unfortunately, the bug does not seemed to be documented correctly so basically if you go to the CUCM Admin page > Device > Phone > Select the CIPC > Search for ‘Settings Access’ and change this option to ‘Disabled’.
You expect that the CIPC locks or grayed out all the settings but it is NOT taking the changes.
An enhancement request was made so that on version 8.6.3.6 the changes are taken correctly. This special engineering version is also available at the download page on www.cisco.com.
http://tools.cisco.com/squish/050Ab
You'll find the version under the drop down menu called Engineering Specials.
I managed to recreate this is in the lab and works like a charm.