Use the Vonage Messages API and the @vonage/messages SDK. Set up an Express server, configure your Vonage account, and create an API endpoint that accepts recipient details and image information. The Vonage SDK handles communication with the API to deliver the MMS.

The Vonage Messages API is a multi-channel API that enables sending messages via various channels like SMS, MMS, WhatsApp, and more. In this tutorial, it's used to send multimedia messages (MMS) containing images and captions.

The private key is crucial for secure authentication with the Vonage API. It's used to sign API requests, ensuring that only authorized applications can access your Vonage account and send messages.

ngrok is useful during development and initial setup when your local server isn't publicly accessible. It creates a temporary public URL that Vonage can use for webhooks, which are necessary for the setup process, even for just sending MMS.

International MMS support is limited. While Vonage primarily supports MMS from US numbers to US recipients, some international options might exist. Consult the Vonage documentation for the most current information on international MMS capabilities and any specific requirements or limitations.

Log into your Vonage dashboard, create a new application, enable the Messages capability, generate and securely store your private key, and link an MMS-capable number to your Vonage application. Set up the necessary webhooks and note your Application ID.

The `private.key` file contains your Vonage application's private key, which is essential for authenticating your application with the Vonage API. It must be kept secure and should not be shared or committed to version control.

Use `npm install express @vonage/messages dotenv` to install the required packages. `express` is the web framework, `@vonage/messages` is the Vonage SDK, and `dotenv` helps manage environment variables.

While the basic MMS sending example doesn't actively use webhooks, Vonage requires them to be set up during application creation. They are typically used for receiving delivery receipts and inbound messages, which might be needed for more advanced functionalities.

Carriers typically impose MMS file size limits, often between 300KB and 1MB. While not explicitly mentioned in the article with respect to Vonage's limits, large files may cause failures, and it's recommended to keep files small or compress them before sending.

The provided code includes robust error handling using try-catch blocks around the API call. It logs errors to the console, attempts to extract specific error messages from the Vonage API response, and returns user-friendly errors to the client.

This error occurs with trial Vonage accounts when you try to send an MMS to a number that hasn't been added to your allowed list in the Vonage dashboard's Sandbox & Test Numbers section. Add the recipient's number to your allowed list to resolve the issue.

The request body must be JSON formatted and should include the recipient's phone number (`to`), the publicly accessible image URL (`imageUrl`), and an optional caption (`caption`). Format phone numbers using E.164.

Implement authentication and authorization for your sending endpoint. Use strong input validation, sanitize user inputs, implement rate limiting to prevent abuse, and use secure methods to manage secrets, avoiding storing them directly in `.env` files.