# Receive an incoming SMS Message

 Note:
Before you can get started, you need the following already set up:

- 
- [NPM](https://www.npmjs.com/) and a familiarity with how to install packages.
- [Node.js](https://nodejs.org/en/) and a familiarity with how to create a new app.
- [ngrok](https://ngrok.com/). You'll use ngrok to open a tunnel to your local server.


Learn how to handle incoming SMS messages in a Node.js application with the Sinch Node.js SDK.

Steps:
1. [Set up](#set-up-your-nodejs-application) your Node.js application
2. [Start](#start-your-web-server-and-set-up-a-tunnel) your web server and set up a tunnel
3. [Send](#send-your-sms-message) your SMS message


## Set up your Node.js application

To quickly get started setting up a simple client application using the Node SDK:

1. If you haven't already, clone the [sinch-sdk-node-quickstart](https://github.com/sinch/sinch-sdk-node-quickstart) repository.
2. Navigate to the `getting-started/sms/respond-to-incoming-message/server` folder.
3. Open a command prompt or terminal and run the following command to install the necessary dependencies:

```shell
npm install
```
4. Open the `.env` [file](https://github.com/sinch/sinch-sdk-node-quickstart/blob/main/getting-started/sms/respond-to-incoming-message/server/.env). Using the [access key credentials](https://dashboard.sinch.com/settings/access-keys) from your Sinch Build Dashboard, add your values:
| Field | Description |
|  --- | --- |
| SINCH_PROJECT_ID | The unique ID of your Project. |
| SINCH_KEY_ID | The unique ID of your access key. |
| SINCH_KEY_SECRET | The secret that goes with your access key.  **Note:** For security reasons, this secret is only visible right after access key creation. |
| SMS_REGION | The region in which you are send and receiving SMS traffic. Use `us` for US traffic and `eu` for European traffic. |
5. Save the file.


## Start your web server and set up a tunnel

1. Start the server by executing the following command:

```shell
npm start
```
2. Open a tunnel to the server you just set up. We are using [ngrok](https://ngrok.com/) for this. If you don't have ngrok installed already, install it with the following command:

```shell
npm install ngrok -g
```
3. Open a terminal or command prompt and enter:

```shell
ngrok http 3001
```
4. You should see a screen in your console that shows the running tunnel. Copy the address ending in `.ngrok.io`.


### Configure your Callback URL

1. To configure a callback URL for your Sinch account, login to your [dashboard](https://dashboard.sinch.com/sms/api/rest).
2. Click on the service plan ID link and edit the Callback URL field with the ngrok.io domain URL from the previous section with `/SmsEvent` added to the end. The complete URL should look something like `https://3b58-75-118-121-186.ngrok-free.app/SmsEvent`.


## Send your SMS message

Now send an SMS message to your Sinch number from your mobile phone and you will get an automatic reply.

## Next steps

The code you used in the `serverBusinessLogic.js` file listens for a webhook sent from the Sinch servers and then sends a POST request to the Sinch API `/batches` endpoint to send the SMS message.

- Explore the [API specification](/docs/sms/api-reference/) to test more endpoints.


## Additional resources

- Click [here to learn more about the batches endpoint](/docs/sms/api-reference/sms/batches).