SIM Bank Backend + SMS API
Publicada el 2026-07-28
Descripción de la oferta
# Needed: SIM Bank Management System + External SMS Provider API Integration (Partner API) ## Overview I have on-premise GSM SIM banks/modems, and I need a system to manage these numbers and expose them as a "supplier" (Partner) to an external SMS service (API details and documentation will be shared directly with the selected engineer), so that any SMS received on any of my numbers is automatically forwarded to that company's servers via their Partner API. **Scale:** A small number of devices/modems, under 1,000 messages/day (no need for a heavy-scale solution — reliability is the priority, not throughput). ## Required Components ### 1. Gateway Agent (runs locally next to the hardware) - Communicates with the modems via AT commands (or whatever protocol the modems support) - Monitors each SIM's health: network registration, signal strength, connection status - Detects a modem that has silently "hung" or lost connection (without the process crashing) and reports it - Receives incoming SMS and forwards them to the Control Plane ### 2. Control Plane (central server, cloud-hosted) - **Number Inventory:** Tracks every number/SIM, its status (available/busy/faulty), and which service it's currently tied to - **Sync with the partner company:** Sends periodic updates on available numbers and services - **Activation Map:** Links each incoming SMS to the correct activation when there's contention (the same SIM receiving multiple requests in a short window) - **Push Worker with internal queue:** Every incoming SMS is stored first (durable — won't be lost if the server crashes), then a separate worker attempts delivery to the partner company via their Partner API (endpoint details to be shared with the engineer after agreement) - Retries periodically until a success response is received - Idempotency: ensuring the same message isn't sent twice if the response is lost even though delivery actually succeeded ### 3. Agent ↔ Control Plane Connection - The hardware is on-premise with no public IP, so the Agent initiates a persistent outbound connection to the Control Plane (WebSocket or MQTT), not the other way around - Automatic reconnect/heartbeat if the connection drops ### 4. Security - Secure storage of the partner company's API key (never exposed in logs or plain code) - Agent ↔ Control Plane communication encrypted (TLS) - An NDA will be required before sharing API details and the partner company's name ## Required Deliverables - [ ] Gateway Agent code (with documentation on installing it on the local server) - [ ] Control Plane code (API + database + worker) - [ ] Full, tested integration with the partner company's Partner API - [ ] A simple dashboard to monitor number and message status (pending/sent/failed) - [ ] Deployment documentation (how to run the system from scratch) - [ ] A test plan: simulating network failure/disconnection and confirming messages aren't lost ## Suggested Tech Stack (flexible — engineer may propose alternatives) - Backend: Node.js or Python - Database: PostgreSQL (sufficient for this scale, no need for Kafka or anything complex) - Agent↔Server connection: MQTT or WebSocket ## What to Include in Your Proposal - Prior experience with GSM modems / AT commands or SIM banks - Experience building systems that rely on external webhooks/APIs with retry logic - Estimated timeline and price - Have you worked with virtual number services / SMS aggregators before (in general terms, no need to name specific companies)?
Skills
Fuente original: freelancer