Managing communication resources having unknown addresses

Communications are managed by determining costs associated with the use of communications resources. Usage data is accessed from a plurality of communications resources and consolidated from system-specific formats to a common format. The costs of communication events that have a recorded duration are determined. A database of communications addresses to identify known addresses is maintained but unknown addresses present in the usage data but not contained in the database are also identified. Users of communication resources to unknown addresses are asked to identify the unknown address in order to update the database. Unknown addresses can be nominated as private addresses.