Origin-Based Rating (OBR) prices call termination by the presented origin of the A-number, not only by the destination. Introduced to make rates reflect real network costs, it created the arbitrage that powers CLI refiling: present a cheaper origin, pay a cheaper rate, and pocket the difference.
Why it matters
Understanding OBR is understanding why refiling exists. Before OBR, the A-number was presentation; after OBR, it is price. Every refiling detection method is, one way or another, an attempt to verify that the presented origin is the true one.
What practitioners watch
Per-hop A-number verification, numbering-plan cross-checks and corridor baseline analytics are the working defences. Commercial pressure on partners whose traffic arrives mispresented completes the loop.
Related: CLI Refiling Observatory · A-Number · CLI