Adherence phone states are kept for a certain period of time. In most cases, the default setting is to retain the phone states for a rolling 90-day timeframe. This means that during the overnight hours the system will remove any phone states that are older than 90 days.
This process is completed on the SQL Server and can only be modified by a Server Admin or CommunityWFM support personnel.
With version 5.x, agent state transaction summary data, which is processed automatically at regular intervals, may be retained indefinitely.