Reply to Incoming SMS Messages Using .NET

Overview

This guide shows how to receive SMS text messages on a Plivo phone number — something you might want to do to acknowledge a request from a customer, handle opt-ins and opt-outs, or implement an autoresponder application.

You can reply to SMS messages either by using our PHLO visual workflow builder or our APIs. Follow the instructions in one of the tabs below.

You can create and deploy a PHLO to reply to an incoming text message with a few clicks on the PHLO canvas.

Prerequisites

To get started, you need a Plivo account — sign up with your work email address if you don’t have one already. To receive incoming messages, you must have a Plivo phone number that supports SMS. You can rent numbers from the Numbers page of the Plivo console, or by using the Numbers API.

Create the PHLO

To create a PHLO, visit the PHLO page of the Plivo console. If this is your first PHLO, the PHLO page will be empty.

  • Click Create New PHLO.

  • In the Choose your use case pop-up, click Build my own. The PHLO canvas will appear with the Start node.

    Note: The Start node is the starting point of any PHLO. It lets you trigger a PHLO to start upon one of three actions: incoming SMS message, incoming call, or API request.

  • From the list of components on the left-hand side, drag and drop the Send Message component onto the canvas. When a component is placed on the canvas it becomes a node.

  • Draw a line to connect the Start node’s Incoming Message trigger state to the Send Message node.

  • In the Configuration pane at the right of the canvas, configure the Send Message node with a sender ID in the From field. Enter as the To number the number from which you received the message that triggered the reply. Put your message in the Message field.

  • Once you’ve configured the node, click Validate to save the configuration.

  • After you complete the configuration, give the PHLO a name by clicking in the upper left, then click Save.

Assign the PHLO to a Plivo number

Once you’ve created and configured your PHLO, assign it to a Plivo number.

  • On the Numbers page of the console, under Your Numbers, click the phone number you want to use for the PHLO.

  • In the Number Configuration box, select PHLO from the Application Type drop-down.

  • From the PHLO Name drop-down, select the PHLO you want to use with the number, then click Update Number.

Assign PHLO to a Plivo Number

Test

You can now send a message to your Plivo phone number and see that a reply is generated.

For more information about creating a PHLO application, see the PHLO Getting Started guide. For information on components and their variables, see the PHLO Components Library.

Here’s how to use Plivo APIs to reply to incoming SMS text messages.

Prerequisites

To get started, you need a Plivo account — sign up with your work email address if you don’t have one already. To receive incoming messages, you must have a Plivo phone number that supports SMS; you can rent numbers from the Numbers page of the Plivo console or by using the Numbers API. If this is your first time using Plivo APIs, follow our instructions to set up a .NET development environment and a web server and safely expose that server to the internet.

Create an MVC controller to reply to messages

In Visual Studio, create a new project. Use the template for Web Application (Model-View-Controller).

Create an MVC app

Give the project a name — we used ReplySMS.

Navigate to the Controllers directory in the ReplySMS project. Create a controller named ReplysmsController.cs and paste into it this code.

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using System;
using System.Collections.Generic;
using Microsoft.AspNetCore.Mvc;

namespace Replysms.Controllers
{
    public class ReplysmsController : Controller
    {
        // GET: /<controller>/
        public IActionResult Index()
        {
            String from_number = Request.Form["From"];
            String to_number = Request.Form["To"];
            String text = Request.Form["Text"];
			Plivo.XML.Response resp = new Plivo.XML.Response();
			resp.AddMessage("Thank you, we received your request",new Dictionary<string, string>()
			{
				{"src", to_number},
				{"dst", from_number},
				{"type", "sms"}
			});
			var output = resp.ToString();
			Console.WriteLine(output);
			return this.Content(output, "text/xml");
		}
    }
}

Expose your local server to the internet.

Create a Plivo application to reply to messages

Associate the controller you created with Plivo by creating a Plivo application. Visiting Messaging > Applications and click Add New Application. You can also use Plivo’s Application API.

Give your application a name — we called ours Reply Incoming SMS. Enter the server URL you want to use (for example http://<yourdomain>.com/replysms/) in the Message URL field and set the method to POST. Click Create Application to save your application.

Create Application

Assign a Plivo number to your application

Navigate to the Numbers page and select the phone number you want to use for this application.

From the Application Type drop-down, select XML Application.

From the Plivo Application drop-down, select Reply Incoming SMS (the name we gave the application).

Click Update Number to save.

Assign Phone Number to Reply SMS App

Test

Send a text message to the Plivo number you specified using any phone. You should receive a reply.