| Customer Account Model | Organizes customers, billing accounts, and subscriptions into a clean hierarchy — so invoices always go to the right place |
| Pricing Engine | Defines how much to charge — rate cards, usage-based rules, tiered pricing, RUBS, and multi-condition charging logic |
| Billing Engine | Turns pricing into invoices at scale — bill runs, draft review, usage ingestion, meter reads, and arrears carry-forward |
| AR Management | Everything after the invoice — credit notes, cash application, aging schedules, late payment charges, and customer subledgers backed by a formal ledger |
