Build a Node.js Express App for Bulk SMS with Sinch - code-examples -

Frequently Asked Questions

Use the Sinch SMS REST API with a Node.js Express app. This allows you to send a single message to multiple recipients by making a POST request to the /batches endpoint. The request should include an array of phone numbers and the message content. This approach is significantly more efficient than sending individual messages and allows for scalable broadcasts.
The Sinch /batches endpoint is designed for efficient bulk SMS messaging. It enables sending the same SMS message to multiple recipients in a single API call, rather than sending numerous individual messages, thus optimizing performance and cost-effectiveness. It expects an array of recipient phone numbers and the message body in the request payload.
Store your Sinch `SERVICE_PLAN_ID`, `API_TOKEN`, `SINCH_NUMBER`, and `SINCH_BASE_URL` as environment variables in a `.env` file. Use the `dotenv` package in your Node.js project to load these variables into your application's environment. This practice keeps your credentials out of your codebase, enhancing security.
Bulk SMS sending leverages Sinch's optimized infrastructure to deliver messages to multiple recipients with a single API call. This reduces overhead compared to iteratively sending individual messages, resulting in improved speed and efficiency. The Sinch /batches endpoint is specifically designed for this type of broadcast.
Consider a message queue for high-volume bulk SMS sending, typically for broadcasts reaching tens of thousands of recipients or more. Queuing decouples the API request from the actual SMS delivery process, enabling your application to handle requests quickly without being slowed down by the time it takes to submit the batch to the Sinch API.
Always use the E.164 format for recipient phone numbers when sending SMS messages via the Sinch API. This international standard includes a plus sign (+), the country code, and the subscriber number without any spaces or dashes (e.g., +12025550147). Proper formatting is crucial for successful delivery.
Yes, you can enable delivery reports (DLRs) in your Sinch API requests and configure a webhook URL in your Sinch account settings. Sinch will then send POST requests to your specified webhook URL with delivery updates for each message. This allows you to track successful deliveries, failures, and other delivery statuses.
Implement robust error handling by catching potential errors from Axios when making requests to the Sinch API. Inspect the error object, specifically `error.response.data` for detailed information provided by Sinch about the issue. Handle different error codes (4xx, 5xx) appropriately, providing informative error messages and potentially retrying requests for transient errors.
Log key information such as incoming request details, successful batch submissions with batch IDs, and any errors encountered. For errors, include detailed information from the Sinch API response, such as status codes and error messages. Use a structured logging format, like JSON, for easier parsing and analysis in production environments.
Use the `express` package in Node.js to create an app, define routes, and handle requests. Set up middleware to parse JSON request bodies (`app.use(express.json())`). Define an API endpoint, such as `/api/broadcast`, to handle the incoming requests for sending bulk SMS messages. Include error handling middleware to catch and process errors gracefully.
Axios is a promise-based HTTP client used to make HTTP requests to the Sinch API from your Node.js application. It simplifies the process of making API calls, handling responses, and managing asynchronous operations. Axios also provides features for handling errors and network issues.
Protect your API keys by storing them in environment variables (`.env`) and excluding this file from version control (`.gitignore`). Implement input validation and sanitization to prevent invalid data from reaching the Sinch API. Consider using rate limiting to protect against abuse. Run your app behind HTTPS and implement authentication/authorization if needed.
Common errors include 401 Unauthorized (check API credentials), 400 Bad Request (verify phone numbers, request body), 403 Forbidden (check number permissions), and 5xx Server Errors (retry with backoff). Carefully inspect `error.response.data` for detailed error messages from Sinch to diagnose and resolve issues.
Create a clear project structure with directories like `src/`, `controllers/`, `routes/`, `services/`. This promotes maintainability. The `src/app.js` file initializes the Express app, `controllers` handle request logic, `routes` define endpoints, and `services` encapsulate API interaction logic.