Whcih version of CCM ?
In CCM 4.x and up...
Under Enterprise PArameters...
DSCP for Cisco CallManager to Device Interface : This parameter specifies the Differentiated Service Code Point (DSCP) IP classification for protocol control interfaces that are used in Cisco CallManager-to-device communications. Note: You must restart Cisco CallManager servers and associated devices for this parameter change to take effect.
This is a required field.
Default: CS3(precedence 3) DSCP (011000).
Restart the Cisco CallManager service and associated devices for the parameter change to take effect.