The following links will provide you with the function of each service in CallManager CCM 4.x http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/admin/4_1_3/ccmsys/a02svcs.html CUCM 5.x, 6.x, 7.x http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/se...