Reply to Incoming SMS Messages Using Go

    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.

    To reply incoming SMS, you can create and deploy a PHLO with a few clicks on the PHLO canvas. PHLO also lets you visually construct your entire use-case. With PHLO, you only pay for SMS you send/receive, and building with PHLO is free. You can refer to the below instructions in the Using PHLO tab to begin your implementation.

    Implementation

    In this section, we will guide you to create a PHLO to Reply Incoming SMS.

    Prerequisites

    1. Create a Plivo Account(if you don’t have one already): You can sign up with your work email address and complete the phone verification step using your mobile number.
    2. Plivo Phone Number(Optional): To receive SMS, you must have a Plivo phone number that supports SMS. Numbers can be purchased from the Numbers section of your Plivo Console and use the same as the source number/from number for the outbound SMS. This number will also help you receive incoming SMS as you must have a SMS-enabled Plivo phone number to do the same. Please note that you can also purchase numbers using the Numbers API.

    Create the PHLO

    You can create a PHLO by referring to the below instructions to Reply Incoming SMS:

    Create a PHLO to Reply Incoming SMS

    • On the side navigation bar, click PHLO. The PHLO page will appear and display your existing PHLOs, if any exist. If this is your first PHLO, then the PHLO page will be empty.
    • Click Create New PHLO to build a new PHLO.
    • In the Choose your use-case window, click Build my own. The PHLO canvas will appear with the Start node.
      Note: The Start node is the starting point of any PHLO. You can choose between the four available trigger states of the start node; Incoming SMS, Incoming Call, and API Request. For this PHLO, we will use the Incoming Message trigger state.
    • From the list of components on the left-hand side, drag and drop the Send Message component onto the canvas. This will add a HTTP Request node onto the canvas.
    • Connect the Start node with the Send Message node, using the Incoming Message trigger state.
    • Configure the Send Message node to send the details as shown in the above gif.
    • Once you have configured the node, click Validate to save the configurations.
    • After you complete the configurations, provide a recognizable name for your PHLO and click Save. Your PHLO is now ready.

    Assign the PHLO to a Plivo Number for Incoming SMS

    Once you have created and configured your PHLO, assign your PHLO to a Plivo number.

    To assign a PHLO to a number

    1. Log in to your Plivo Console
    2. On the Product Navigation bar, click Phone Numbers.
    3. On the Numbers page, under Your Numbers, click the phone number you wish to use for the PHLO.
    4. In the Number Configuration window, select PHLO from the Application Type list.
    5. From the PHLO Name list, select the PHLO you wish to use with the phone number, and then click Update Number.

    Assign PHLO to a Plivo Number

    If you have not purchased a phone number yet, you can buy a phone number(s) by referring to the instructions available here.

    Test and Validate

    You can now receive a message to your Plivo phone number to reply an incoming SMS and see how reply incoming SMS is handled using PHLO.

    For more information about creating a PHLO app, see the PHLO User Guide.
    For information on components and their variables, see the PHLO Components Library.

    To reply incoming SMS, you can refer to the instructions in the following section to begin your implementation.

    Implementation

    In this section, we will guide you in setting up an app to Reply Incoming SMS received on your Plivo number.

    Prequisites

      1. Plivo account: Sign up for a Plivo account if you don’t have one already.
    1. Plivo phone number:: To receive SMS, you must have a Plivo phone number that supports SMS. You can purchase numbers from the Numbers page of the Plivo console or by using the Numbers API.

    Buy a New Plivo Number

    Set Up Go Server to Reply Incoming SMS

    In this section, we’ll walk you through how to set up a Go server in under five minutes and start Reply Incoming SMS.

    Install Go

    You can install Go from the Official Installer.

    Install Plivo Go Package

    • Create a project directory, run the following command:

      $ mkdir mygoapp
      
    • Change the directory to our project directory in the command line:

      $ cd mygoapp
      
    • You can install the Plivo Go package using the go command.

      $ go get github.com/plivo/plivo-go
      
    • You can also install by cloning this repository into your GOPATH.

    Create a Go Server to Reply Incoming SMS

    Use the following code snippet to start a local server.

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    package main
    
    import (
    	"net/http"
    	"plivo-go/xml"
    )
    
    func handler(w http.ResponseWriter, r *http.Request) {
    	fromnumber := r.FormValue("From")
    	tonumber := r.FormValue("To")
    	text := r.FormValue("Text")
    	print("Message Received - ", fromnumber, " ", tonumber, " ", text)
    
    	response := xml.ResponseElement{
    		Contents: []interface{}{
    			new(xml.MessageElement).
    				SetDst(tonumber).
    				SetSrc(fromnumber).
    				SetContents("Thank you, we have received your request."),
    		},
    	}
    	w.Write([]byte(response.String()))
    }
    
    func main() {
    	http.HandleFunc("/reply_sms/", handler)
    	http.ListenAndServe(":8080", nil)
    }
    

    Save this code in any file (name the file something like reply_sms.go). To run this file on the server, go to the folder where this file resides and use the following command:

    $ go run reply_sms.go
    

    And you should see your basic server app in action on http://localhost:8080/reply_sms/

    Exposing your local server to the internet

    To Reply Incoming SMS and to handle callbacks, your local server should be able to connect with Plivo API service, Ngrok is a tunneling software used to expose a web server running on your local machine to the internet. Using Ngrok you can set webhooks which can talk to Plivo server.

    ngrok block diagram

    You can download and install ngrok from here. Follow the detailed configuration instructions to get started.

    Run ngrok on the port which currently hosts your application. For example, if your port number is 80, run the following command:

    ./ngrok http <port_on_which_your_local_server_is_running>
    

    This will give you a UI with links that look like ngrok.io/* which you can use to access your local server using the public network.

    Sample ngrok CLI

    Create an Application

    1. Create an Application by visiting the Application Page and click on New Application. You can also use Plivo’s Application API.
    2. Give your application a name. Let’s call it Reply incoming SMS. Enter your server URL (e.g. http://example.com/replysms/) in the Message URL field and set the method as POST. See our Application API docs to learn how to modify your application through our APIs.
    3. Click on Create Application to save your application.

    Create Application

    Assign a Plivo number to your app

    1. Navigate to the Numbers page and select the phone number you want to use for this app.
    2. Select Reply SMS (name of the app) from the Plivo App dropdown list.
    3. Click on Update to save.

    Assign Phone Number to Reply SMS App

    Test and validate

    Using a normal mobile phone, send SMS to your Plivo number. Plivo will send a request to your Message URL with the parameters mentioned in the Messages Documentation and reply the message to the specified destination.