I've got an upcoming project to do some coding/customisation on an Open Source billing system, so figured I would spend the evening exploring how it's put together. It is far less involved than even the VoIP plug-in to the billing system I just finished, let alone the system I'm contemplating building. It has no dependency negotiation I can detect. It's basically just a set of X packages with Y options. I haven't found an inventory-control system yet, though I'm told it exists somewhere.

That said, it does have a few minor features that we could use (and which I already spec'd as requirements for the new system). However, the product doesn't have the core systems that would be needed to produce a full-blown rule-based billing/provisioning system; which means I'll likely create my own new project rather than integrating with it.

Anyway, have a fairly good idea of the capability and structure of the system now. I think I'll consider that the evening's work and head off to bed.