The call records are stored in the CDR database on the publisher's SQL Server. Subscribers don't have a CDR database - they send their call records to the publisher to get inserted into it's CDR database, so the Publisher's CDR database contains call records for the entire cluster.
You can use the SQL applications such as Enterprise Manager or Query Analyzer on the Publisher to examine the CDR database. The CallDetailRecord table in the CDR database contains the call records, and the CallDetailRecordDiagnostic table contains the CMR, which are QoS records produced by devices such as IP Phones and MGCP gateways.
Here is the specification for call records on CallManager 4.1:
http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_programming_usage_guide09186a0080405548.html
The specification is very useful for learning about the fields and formats of the call records, but if you don't want to work with "raw" call records, then you can use a 3rd party billing application, or something like ART (Administrative Reporting Tool) to produce some reports from CDR. See the ART links at the top of this page:
http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_user_guide_list.html
Call records are not created by default - you have to enable them on each CallManager in the cluster. Go to the CallManager settings in Service Parameters and look for the "Cdr Enabled" setting, which you'll note is false by default. If you would also like QoS records (also known as CMR), then you will also want to enable the Call Diagnostics setting, which is also in CallManager Service Parameters. You will also have to enable the Cdr Insert service on the Publisher.
Call records on the CallManager are more complex than on other PBXs that you might be used to, so if you are going to work with raw cdr, you will find the specification useful.
