Voicemail Transcription Using Ruby

    Overview

    This guide shows how to transcribe voicemail and send the transcription via SMS.

    Prerequisites

    To get started, you need a Plivo account — sign up with your work email address if you don’t have one already. You must have a voice- and SMS-enabled Plivo phone number to receive calls and send SMS messages; 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 Ruby development environment and a web server and safely expose that server to the internet.

    Create a Rails controller to implement voicemail transcription

    Change to the project directory and run this command to create a Rails controller for inbound calls.

    $ rails generate controller Plivo voice
    

    This command generates a controller named plivo_controller in the app/controllers/ directory and a respective view in app/views/plivo. We can delete the view as we do not need it.

    $ rm app/views/plivo/voice.html.erb
    

    Edit app/controllers/plivo_controller.rb and paste this code into the PlivoController class.

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    include Plivo
    include Plivo::XML
    include Plivo::Exceptions
    
    class PlivoController < ApplicationController
      skip_before_action :verify_authenticity_token
    	def voicemail
    		response = Response.new
    		response.addSpeak('Please leave a message after the beep. Press the star key when you\'re done.')
    		params = {
          		transcriptionType: 'auto',
          		transcriptionUrl: url_for(action: 'transcriptionUrl', controller: 'plivo', only_path: false, protocol: 'https'),
    			action: url_for(action: 'actionUrl', controller: 'plivo', only_path: false, protocol: 'https'),
    			maxLength: '30',
    			finishOnKey: '*'
    		}
    		response.addRecord(params)
    
    		second_speak_body = 'Recording not received.'
    		response.addSpeak(second_speak_body)
    				xml = PlivoXML.new(response)
    		render xml: xml.to_xml
    	end
    
      def transcriptionUrl
        response = params
    		api = RestClient.new("<auth_id>","<auth_token>")
    		message_response = api.messages.create(
    			src: "<sender_id>",
    			dst: "<destination_number>",
    			text: "You have a new transcription: "+params[:transcription]
    		)
    		puts message_response
    		puts response
        render status: :ok, json: @controller.to_json
      end
    
      def actionUrl
        response = params
        puts response
        render status: :ok , json: @controller.to_json
      end
    end
    

    Replace the auth placeholders with your authentication credentials from the Plivo console. Replace the phone number placeholders with actual phone numbers in E.164 format (for example, +12025551234).

    Add a route

    To add a route for the inbound function in the PlivoController class, edit config/routes.rb and add this line after the inbound route.

      post 'plivo/voicemail'
      post 'plivo/transcriptionUrl'
      post 'plivo/actionUrl'
    

    Start the Rails server

    $ rails server
    

    You should see your basic server application in action at http://localhost:3000/plivo/voicemail/.

    Set up ngrok to expose your local server to the internet.

    Note: For ngrok testing, add this line to config/environments/development.rb.
    config.hosts << /[a-z0-9-]+\.ngrok\.io/

    Create a Plivo application for voicemail transcription

    Associate the Rails controller you created with Plivo by creating a Plivo application. Visit Voice > Applications in the Plivo console and click on Add New Application, or use Plivo’s Application API.

    Give your application a name — we called ours Voicemail-Transcription. Enter the server URL you want to use (for example https://<yourdomain>.com/voicemail/) in the Answer URL field and set the method to POST. Click Create Application to save your application.

    Plivo Create Application Voicemail Transcription

    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 Voicemail-Transcription (the name we gave the application).

    Click Update Number to save.

    Assign Voicemail Application

    Test

    Make a call to your Plivo number and leave yourself a voicemail message. You should receive a text message with the transcription.

    Note: If you’re using a Plivo Trial account, you can send SMS 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.