Hi Ayaz,
You probably need to check the Auto - Purge config;
CCM>applicaitons>cisco callmanager servicibility> cdr analysis and reporting> system> database> configure automatic purge.
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/service/4_1_3/ccmsrva/sacar2.pdf
Cheers!
Rob
"May your heart always be joyful
May your song always be sung" - Bob Dylan