Items in the CMS database can be either call-based or interval-based. Most CMS database items are call-based. Call-based data is committed to the database after a call completes. Therefore, if a call starts and ends in different collection intervals, all of the data are recorded in the interval in which the call and any After Call Work (ACW) are completed.

Interval-based data represents the amount of time during a collection interval that is used for a particular activity. Interval-based items are updated throughout the collection interval and timing is restarted at the end of the interval. Most interval-based items start with I_ or TI_. The database items ALLINUSETIME (trunk-group tables) and MBUSYTIME (trunk and trunk-group tables) are also interval-based.

Each database item has a defined column type.