How to Send and Receive SMS Messages Using .NET and Plivo's Messaging API

Your company has settled on Plivo to handle its voice and messaging communications, and now it’s your job to start integrating Plivo into your company’s applications. Don’t worry — Plivo has a .NET SDK to help you out. You can use it write .NET applications that send and receive SMS messages.

Prerequisites

To get started, you need a Plivo account — sign up with your work email address if you don’t have one already. If this is your first time using Plivo APIs, follow our instructions to set up a .NET development environment.

Send an SMS message

Now you’re ready to start. Open the file Program.cs in the CS project and paste into it this code.

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using System;
using System.Collections.Generic;
using Plivo;

namespace testplivo
{
    internal class Program
    {
        public static void Main(string[] args)
        {
            var api = new PlivoApi("<auth_id>","<auth_token>");
            var response = api.Message.Create(
                src: "<sender_id>",
                dst: "<destination_number>",
                text: "Hello, world!"
                );
            Console.WriteLine(response);
        }
    }
}

Replace the auth placeholders with actual values from the Plivo console. Replace the phone number placeholders with actual phone numbers in E.164 format (for example, +12025551234). In countries other than the US and Canada you can use a sender ID for the message source. You must have a Plivo phone number to send messages to the US or Canada; you can rent a Plivo number from Phone Numbers > Buy Numbers on the Plivo console or via the Numbers API. Save the file and run it.

$ dotnet run

Note: If you’re using a Plivo Trial account, you can send messages only to phone numbers that have been verified with Plivo. You can verify (sandbox) a number by going to the console’s Phone Numbers > Sandbox Numbers page.

Receive an SMS message

Of course sending messages is only half of the equation. Plivo supports receiving SMS text messages in many countries (see our SMS API coverage page and click on the countries you’re interested in). When someone sends an SMS message to a Plivo phone number, you can receive it on your server by setting a Message URL in your Plivo application. Plivo will send the message along with other parameters to your Message URL.

Begin by setting up a .NET Core app. Create a new project directory.

$ mkdir receivesmsapp

Change to that directory and initialize the model-view-controller (MVC) architecture with the command

$ dotnet new mvc --no-https

Change to the Controllers directory. Create a controller named ReceiveSmsController.cs and paste into it this code.

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using System;
using Microsoft.AspNetCore.Mvc;

namespace ReceiceSms.Controllers
{
    public class ReceiveSmsController : Controller
    {
        // GET: /<controller>/
        public String Index()
        {
            // Sender's phone number
            String from_number = Request.Form["From"];
            // Receiver's phone number
            String to_number = Request.Form["To"];
            // The text that was received
            String text = Request.Form["Text"];
            // Print the message
            Console.WriteLine("Message received - From: {0}, To: {1}, Text: {2}", from_number, to_number, text);

            return "Message received";
        }
    }
}

Before you can test the application, edit Properties/launchSettings.json and set the applicationUrl.

"applicationUrl": "http://localhost:5000/"

Then start the local server with the command

$ dotnet run

You should then be able to see your basic server app in action on http://localhost:5000/receivesms/.

That’s fine for testing, but it’s not much good if you can’t connect to the internet to receive incoming messages and handle callbacks. For that, we recommend using ngrok, which exposes local servers behind NATs and firewalls to the public internet over secure tunnels. Install it and run ngrok on the command line, specifying the port that hosts the application on which you want to receive messages.

$ ./ngrok http [portnum]

Ngrok will display a forwarding link that you can use as a webhook to access your local server using the public network.

Now you can create an application to receive SMS messages (follow our Quickstart guide for details).

Conclusion

And that’s all there is to sending and receiving SMS messages using Plivo’s .NET Core SDK. Don’t use .NET Core? Don’t worry — we have SDKs for Java, Python, PHP, Node.js, Ruby, .NET Framework, and Go.

Haven’t tried Plivo yet? Getting started is easy and only takes five minutes. Sign up today.