Reporting Question

I’ve got a FreePBX (v2.5.1.0) which serves as the phone system for 3 small companies, and provides an inbound and outbound trunk to a 4th small company (which has their own Trixbox). I’d like to show my bosses a report indicating how much of the total traffic is used by each small company for the sake of cost segregation. Sadly, I think the only identifiers I have for each company are their extensions (and the 4th uses a trunk, which ought to be easy to separate). I’d like to be able to report on both inbound and outbound traffic use. Anybody got a suggestion as to how to create this report? Thanks!