Trunk Usage Report?

I just started with my company who has an Asterisk phone system with FreePBX (first time experience with this phone system). We have a few people who have told me that when they dial to an outside number, they get an all circuits are busy message. I looked in the Reports section in FreePBX, but there is no report to show trunk access usage. I can run reports on incoming calls since they hit a ring group and I can run a report on that particular group extension, but that does not show me outgoing calls. I called our phone service provider, but since we have POTS lines, they have no data for us.

Any idea of how to see if we are using all 12 lines we currently have connected?