SMS Core Function

Every message carries a per-error-code retry policy, a validity period parsed from SMPP absolute or relative time formats, and an expiry sweep. Retries are claimed atomically across instances, so two nodes never double-deliver the same message, and a per-subscriber lock prevents an MT burst from racing itself.

SMS-CF holds its own Diameter client to the OCS — real credit-control requests, segment-based unit charging, and refund handling when a delivery ultimately fails after credit was already reserved.

Destination selection matches on regular expressions against from/to, rewrites the number if needed, and picks a destination from a round-robin or failover list — falling back to a CAPIF pool when nothing else applies. An ENUM/NAPTR lookup resolves the local routing number for ported subscribers before the message ever reaches a destination.

Every step — received, routing match, MT attempt, delivered or failed, delivery receipt, Ro charged or credit denied, refund — is written to an EDR, so a support engineer can reconstruct exactly what happened to a specific message without guessing.

SMS-CF ships an MCP (Model Context Protocol) server exposing three read-only tools — trace a subscriber's message history, check system health, validate configuration — gated by an API key and a hard-coded path allowlist, so an AI assistant can help diagnose an issue without ever reaching an endpoint that changes anything.