Voice OTP Using Ruby

    Overview

    This guide shows how to use a voice one-time password (OTP) to verify a mobile number. We first make a call to the phone number to be verified and use text-to-speech to read a random sequence of digits to the call recipients. The user then confirms the digits by entering them using dialpad keypresses. Voice OTP is commonly used to verify new user registrations for an app or website.

    You can send a voice OTP either by using our PHLO visual workflow builder or our APIs and XML documents. Follow the instructions in one of the tabs below.

    You can create a PHLO to implement a voice OTP with a few clicks on the PHLO canvas and trigger it with a few lines of code.

    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 triggering a PHLO with Ruby, follow our instructions to set up a Ruby development environment.

    Create the PHLO

    Create a PHLO for Voice OTP

    • On the PHLO page of the Plivo console, 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.
    • Click the Start node to open the Configuration tab to the right of the canvas, then enter the keys that you want to retrieve from the HTTP Request payload — in this case, from and to numbers and an OTP.

    • Validate the configuration by clicking Validate. Every time you finish configuring a node, click Validate to check the syntax and save your changes.

    • From the list of components on the left side, drag and drop the Initiate Call component onto the canvas. This adds an Initiate Call node onto the canvas. When a component is placed on the canvas it becomes a node.

    • Draw a line to connect the Start node‘s API Request trigger state to the Initiate Call node.

    • In the Configuration tab of the Initiate Call node, give the node a name. To enter dynamic values for fields, enter two curly brackets to view all available variables, and choose the appropriate ones: {{Start.http.params.from}} for the From field and {{Start.http.params.to}} for the To field, for example. The values for the variables will be retrieved from the HTTP Request payload you defined in the Start node.

    • Next, drag and drop the Play Audio component onto the canvas. Connect the Initiate Call node to the Play Audio node using the Answered trigger state.

    • Configure the Play Audio node to play a message to the user by entering text in the Speak Text box in the Prompt section of its Configuration tab.

      Under Speak Text, tick Amazon Polly as the text-to-speech processor and paste this XML code into the box:

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    <Speak voice="Polly.Amy">
        <prosody rate="medium">
            Your verification code is
        <break/>
        <break/>
        <say-as interpret-as="spell-out">{{Start.http.params.otp}}</say-as>
        </prosody>
    </Speak>
    
    • After you complete and validate the node configurations, give the PHLO a name by clicking in the upper left, then click Save.

    Your PHLO is now ready to test.

    Trigger the PHLO

    You integrate a PHLO into your application workflow by making an API request to trigger the PHLO with the required payload — the set of parameters you pass to the PHLO. You can define a static payload by specifying values when you create the PHLO, or define a dynamic payload by passing values through parameters when you trigger the PHLO from your application. An OTP application always uses a dynamic payload.

    Create a Rails controller for OTP

    Change to the project directory and run this command to create a Rails controller for voice OTP.

    rails generate controller Plivo voice
    

    This generates a controller named plivo_controller in the app/controllers/ directory and a respective view in the app/views/plivo directory. We can delete the view as we don‘t need it.

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

    Edit app/controllers/plivo_controller.rb and paste into it this code.

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    include Plivo
    require 'redis'
    require 'json'
    include Plivo::Exceptions
    
    class PlivoController < ApplicationController
    	def dispatch_otp
    		redis = Redis.new(host: "localhost")
    		code = rand(999_999)
    		dst_number = params[:dst_number]
    		auth_id = '<auth_id>'
        auth_token = '<auth_token>'
    
        client = Phlo.new(auth_id, auth_token)
        	begin
        phlo = client.phlo.get('<phlo_id>')
        #parameters set in PHLO - params
        params = {
           from: <caller_id>,
           to: <destination_number>,
           otp: code
      }
      response = phlo.run(params)
      puts response
    rescue PlivoRESTError => e
      puts 'Exception: ' + e.message
    end
    		redis.setex(dst_number, 60, code) # Verification code is valid for 1 minute
    		puts JSON.pretty_generate({ :status=> 'success', :message=> 'verification initiated' })
    	rescue PlivoRESTError => e
    		puts 'Exception: ' + e.message
    	end
    
    	def verify_otp
    		redis = Redis.new(host: "localhost")
    		code = params[:otp]
    		number = params[:number]
    		original_code = redis.get(number)
    		if original_code == code
    			redis.del(number)  # verification successful, delete the code
    			puts JSON.pretty_generate( { :status=> 'success', :message=> 'codes match, number verified'})
    		elsif original_code != code
    			puts JSON.pretty_generate({ :status => "failure", :message=> 'codes do not match, number not verified' })
    		else
    			puts JSON.pretty_generate( { :status=> 'rejected', :message=> 'number not found' })
    		end
    	end
    end
    

    Replace the auth placeholders with your authentication credentials from the Plivo console. Replace the phlo_id placeholder with your PHLO ID from the Plivo console. Replace the parameters with values from the PHLO. Phone number placeholders should be actual phone numbers in E.164 format (for example, +12025551234).

    Add a route

    Add a route for the outbound function in the PlivoController class. Edit the config/routes.rb file and change the line:

    get 'plivo/voice' 
    

    to

    get 'plivo/verify_otp'
    get 'plivo/dispatch_otp'
    

    Test

    Start the Rails server and start Redis.

    rails server
    redis-server
    

    You should see your basic server application in action as below:

    http://localhost:3000/plivo/dispatch_otp?destination_number=<destination_number>
    http://localhost:3000/plivo/verify_otp?destination_number=<destination_number>&otp=<otp>
    

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

    Note: If you’re using a Plivo Trial account, you can make calls 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.

    Here’s how to use Plivo APIs and XML to implement voice OTPs.

    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 Ruby development environment.

    Create a Rails controller

    Change to the project directory and run this command to create a Rails controller for the voice OTP application.

    $ rails generate controller Plivo voice
    

    It 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 don‘t need it.

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

    Create a voice OTP application

    Edit app/controllers/plivo_controller.rb file and add this code.

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    include Plivo
    require 'redis'
    require 'json'
    include Plivo::Exceptions
    
    class PlivoController < ApplicationController
    	def dispatch_otp
    		redis = Redis.new(host: "localhost")
    		code = rand(999_999)
    		dst_number = params[:dst_number]
    		
    		api = RestClient.new("<auth_id>","<auth_token>")
    		begin
    			response = api.calls.create(
    				'<caller_id>',
    				[dst_number],
    				"https://<yourdomain>.com/answer_url/#{code}"
    			)
    			puts response
    		end
    		redis.setex(dst_number, 60, code) # Verification code is valid for 1 min
    		puts JSON.pretty_generate({ :status=> 'success', :message=> 'verification initiated' })
    	rescue PlivoRESTError => e
    		puts 'Exception: ' + e.message
    	end
    	
    	def verify_otp
    		redis = Redis.new(host: "localhost")
    		code = params[:otp]
    		number = params[:number]
    		original_code = redis.get(number)
    		if original_code == code
    			redis.del(number)  # verification successful, delete the code
    			puts JSON.pretty_generate( { :status=> 'success', :message=> 'Codes match — number verified'})
    		elsif original_code != code
    			puts JSON.pretty_generate({ :status => "failure", :message=> 'Codes do not match — number not verified' })
    		else
    			puts JSON.pretty_generate( { :status=> 'rejected', :message=> 'Number not found' })
    		end
    	end
    end
    

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

    Note: We recommend that you store your credentials in the auth_id and auth_token environment variables, to avoid the possibility of accidentally committing them to source control. If you do this, you can initialize the client with no arguments and Plivo will automatically fetch the values from the environment variables. You can use ENV to store environment variables and fetch them when initializing the client.

    Add a route

    Edit the file config/routes.rb and change the line:

    get 'plivo/voice' 
    

    to

    get 'plivo/verify_otp'
    get 'plivo/dispatch_otp'
    

    Test

    Start Rails and Redis.

    $ rails server
    $ redis-server
    

    You should see your basic server application in action as below:

    http://localhost:3000/plivo/dispatch_otp?destination_number=<destination_number>
    http://localhost:3000/plivo/verify_otp?destination_number=<destination_number>&otp=<otp>
    
    Note: If you’re using a Plivo Trial account, you can make calls 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.