Receive an incoming SMS Message

Note:

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

Set all SMS API configuration settings.
.Net Core 3.1 SDK and a familiarity with how to create a new MVC app.
ngrok. You'll use ngrok to open a tunnel to your local server.

Learn how to handle incoming SMS messages in a .Net Core MVC application with the Sinch SMS API.

Steps:

Set up your .NET Core application
Configure your Callback URL
Test the application

Set up your .Net Core application

Create a new folder where you want your app project. Then, open a terminal or command prompt to that location.
Create a new .Net Core MVC app with the following command:
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```
dotnet new mvc
```
Add the Newtonsoft.Json nuget package:
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```
dotnet add package Newtonsoft.Json
```

Modify your application

In the Controllers folder of your project, create a new file named InboundController.cs.

Populate that file with the "Handle receiving an SMS message" code found on this page.

Handle receiving an SMS message

// Find your Service Plan ID and API Token at dashboard.sinch.com/sms/api/rest
using System;
using System.Net.Http;
using System.Net;
using System.Text;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Newtonsoft.Json;

public class InboundSMS
{
    public string body { get; set; }
    public string from { get; set; }
    string id { get; set; }
    string operator_id { get; set; }
    string received_at { get; set; }
    public string to { get; set; }
    string type { get; set; }
}
public class InboundController : Controller
{
    public string servicePlanId = "YOUR_servicePlanId";
    public string apiToken = "YOUR_API_Token";
    
    [HttpPost]
    public async Task<HttpResponseMessage> ReceiveMessage([FromBody]InboundSMS inboundSms)
    {
        HttpResponseMessage res = new HttpResponseMessage();
        try 
        {
            Console.WriteLine(inboundSms.body);
            SMS sms = new SMS(inboundSms.to, new string[] { inboundSms.from }, inboundSms.body);
            var response = await sms.sendSMS(sms, servicePlanId, apiToken);
            Console.WriteLine(sms.body);
            res.StatusCode = HttpStatusCode.OK;

            return res;
        }
        catch
        {
            res.StatusCode = HttpStatusCode.BadRequest;
            return res;
        }
    }
}
public class SMS
{
    public string from { get; set; }
    public string[] to { get; set; } 
    public string body { get; set; }
    
    public SMS(string fromVar, string[] toVar, string bodyVar)
    {
        from = fromVar;
        to = toVar;
        body = "Your message was: " + bodyVar;
    }

    public async Task<string> sendSMS(SMS sms, string servicePlanId, string apiToken)
    {
        using (var client = new HttpClient())
        {
            client.DefaultRequestHeaders.Add("Authorization", "Bearer " + apiToken);
            string json = JsonConvert.SerializeObject(sms);
            var postData = new StringContent(json, Encoding.UTF8, "application/json");
            var request = await client.PostAsync("https://us.sms.api.sinch.com/xms/v1/" + servicePlanId + "/batches", postData);
            var response = await request.Content.ReadAsStringAsync();
            
            return response;
        }
    }
}

Save the file.

Fill in your parameters

Back in the Program.cs file, replace the following values for these parameters with your values:

Parameter	Your value
`YOUR_Sinch_virtual_number`	Any number you've assigned to your Sinch account. Find the number on your Sinch dashboard by clicking the service plan ID link and scrolling to the bottom of the page.
`recipient_number`	The phone number to which you want to send the test SMS message.
`YOUR_servicePlanId`	The API token found on your Sinch dashboard. Click `Show` to reveal your API token.
`YOUR_API_token`	The service plan ID found on your Sinch dashboard.

Save the file.

Build your project

Before executing your code, you must first compile your application. Execute the following command:

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dotnet build

Start your web server and set up a tunnel

Start the server by executing the following command:
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```
dotnet run
```
By default, your web server is started on port 5001.
Open a tunnel to the server you just set up. We are using ngrok for this. If you don't have ngrok installed already, install it with the following command:
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```
npm install ngrok -g
```
Open a terminal or command prompt and enter:
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```
ngrok http https://localhost:5001
```
Copy the HTTPS address that ends with .ngrok.io and add /Inbound/ReceiveMessage to the end of it.

Configure your Callback URL

To configure a callback URL for your Sinch account, login to your dashboard.
Click on the service plan ID link and edit the Callback URL field with the ngrok.io domain URL from the previous step.

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 Inbound.cs file sends a POST request to the Sinch API /batches endpoint to send the SMS message.

Explore the API specification to test more endpoints.

Additional resources

Click here to read more about the batches endpoint.