Screen Incoming Calls

You can create and deploy a PHLO to screen inbound calls with a few clicks on the PHLO canvas, without writing a single line of code.

​

How it works

When you receive a call on a voice-enabled Plivo number, you can control the call flow by associating a PHLO application to that Plivo number. Plivo will fetch the PHLO associated with the number and expect valid instructions via PHLO to handle the call.

​

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 calls, you must have a voice-enabled Plivo phone number. You can rent numbers from the Numbers page of the Plivo console, or by using the Numbers API.

​

Create a PHLO to block a specific number

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

You can create a PHLO to block a specific number or a whole country. This first example shows how to block a specific number.

• 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 side, drag and drop the Branch 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 Call trigger state to the Branch node.

  The branch component splits a workflow by comparing a variable with a value. Based on the conditions, the execution branches into different workflows. In this case, we compare the “from” number to a specific phone number to block.

  In the Configuration panel, enter the caller ID variable {{ "{{Start.call.from" }}}} in Variable to compare field.

  In Operation, select “Is equal to” from the drop-down list.

  In the final field, enter a value to compare: in this case a phone number — for example, 1-202-555-1234.

• The branch component has two output nodes:

  • No Match: When the values do not match
  • Condition1: When the condition matches
  Note: Condition field names are editable. You can change the name if you have multiple values to compare. This makes a PHLO easier to understand.

• Drag and drop the Call forwarding component onto the canvas and connect No Match to it.

• You can leave the Condition1 node empty or attach it to the Hangup component. The calls will be blocked in either case.

• Click Validate to save the configuration.

• Give the PHLO a name by clicking in the upper left, then click Save.

​

Create a PHLO to block a country

This example shows how to block calls from a whole country.

• 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 side, drag and drop the Branch 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 Call trigger state to the Branch node.

  The branch component splits a workflow by comparing a variable with a value. Based on the conditions, the execution branches into different workflows. In this case, we compare the two-character ISO country code to block calls from a specific country.

  In the Configuration panel, enter the ISO code variable {{ "{{Start.call.from_iso2" }}}} in Variable to compare field.

  In Operation, select “Is equal to” from the drop-down list.

  In the final field, enter a value to compare: in this case the ISO code for the country you want to block.

• The branch component has two output nodes:

  • No Match: When the values do not match
  • Condition1: When the condition matches
  Note: Condition field names are editable. You can change the name if you have multiple values to compare. This makes a PHLO easier to understand.

• Drag and drop the Call forwarding component onto the canvas and connect No Match to it.

• You can choose to leave the Condition1 node empty or attach it to the Hangup component. The calls will be blocked in either case.

​

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.

​

Test

You can now make a call to your Plivo phone number from a blocked phone number or country and see that the call is rejected. If you make a call from any other number, the call should be forwarded as specified in the PHLO.

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 a Plivo XML document that screens incoming calls on a Plivo number.

How it works

Plivo requests an answer URL when it answers the call (step 2) and expects the file at that address to hold a valid XML response from the application with instructions on how to handle the call. In this example, when an incoming call is received, we check whether the number has been blacklisted. If it has, we reject the call using the Hangup XML element. If the phone number hasn’t been blacklisted, we return a Speak XML element that says, “Hello, how are you today.”

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-enabled Plivo phone number to receive incoming calls; 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 Node.js development environment and a web server and safely expose that server to the internet.

Create an Express server to screen incoming calls

Create a file called screen_call.js and paste into it this code.

var plivo = require('plivo');
var express = require('express');
var bodyParser = require('body-parser');
var app = express();

app.use(bodyParser.urlencoded({extended: true}));
app.set('port', (process.env.PORT || 5000));

app.all('/screen_call/', function(request, response) {
    var blacklist = [ '<phone_number1>', '<phone_number2>', '<phone_number3>'];
    // Get the caller's phone number from the 'From' parameter
    var from_number = request.query.From || request.body.From;
    var r = plivo.Response();
    if (blacklist.indexOf(from_number) === -1){
        var body = "Hello, how are you today";
        r.addSpeak(body);
    } else {
        //Specify the reason for hangup

        var params = {'reason': "rejected"};
        r.addHangup(params);
    }
    console.log (r.toXML());
    response.set({'Content-Type': 'text/xml'});
    response.send(r.toXML());
});

app.listen(app.get('port'), function() {
    console.log('Node app is running on port', app.get('port'));
});

Replace the phone number placeholders with actual phone numbers (for example, 12025551234).

Create a Plivo application to screen calls

Associate the Express server 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 Screen Call. Enter the server URL you want to use (for example https://<yourdomain>.com/screen_call/) in the Answer URL field and set the method to POST. Click Create Application to save your 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 Screen Call (the name we gave the application).

Click Update Number to save.

Test

Make a call to your Plivo number using any phone. Plivo will send a request to the answer URL you provided requesting an XML response and then process the call according to the instructions in the XML document the server provides. If your phone number is not blacklisted, the call will go through and you should hear, “Hello, how are you today.”

You can create and deploy a PHLO to screen inbound calls with a few clicks on the PHLO canvas, without writing a single line of code.

​

How it works

When you receive a call on a voice-enabled Plivo number, you can control the call flow by associating a PHLO application to that Plivo number. Plivo will fetch the PHLO associated with the number and expect valid instructions via PHLO to handle the call.

​

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 calls, you must have a voice-enabled Plivo phone number. You can rent numbers from the Numbers page of the Plivo console, or by using the Numbers API.

​

Create a PHLO to block a specific number

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

You can create a PHLO to block a specific number or a whole country. This first example shows how to block a specific number.

• 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 side, drag and drop the Branch 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 Call trigger state to the Branch node.

  The branch component splits a workflow by comparing a variable with a value. Based on the conditions, the execution branches into different workflows. In this case, we compare the “from” number to a specific phone number to block.

  In the Configuration panel, enter the caller ID variable {{ "{{Start.call.from" }}}} in Variable to compare field.

  In Operation, select “Is equal to” from the drop-down list.

  In the final field, enter a value to compare: in this case a phone number — for example, 1-202-555-1234.

• The branch component has two output nodes:

  • No Match: When the values do not match
  • Condition1: When the condition matches
  Note: Condition field names are editable. You can change the name if you have multiple values to compare. This makes a PHLO easier to understand.

• Drag and drop the Call forwarding component onto the canvas and connect No Match to it.

• You can leave the Condition1 node empty or attach it to the Hangup component. The calls will be blocked in either case.

• Click Validate to save the configuration.

• Give the PHLO a name by clicking in the upper left, then click Save.

​

Create a PHLO to block a country

This example shows how to block calls from a whole country.

• 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 side, drag and drop the Branch 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 Call trigger state to the Branch node.

  The branch component splits a workflow by comparing a variable with a value. Based on the conditions, the execution branches into different workflows. In this case, we compare the two-character ISO country code to block calls from a specific country.

  In the Configuration panel, enter the ISO code variable {{ "{{Start.call.from_iso2" }}}} in Variable to compare field.

  In Operation, select “Is equal to” from the drop-down list.

  In the final field, enter a value to compare: in this case the ISO code for the country you want to block.

• The branch component has two output nodes:

  • No Match: When the values do not match
  • Condition1: When the condition matches
  Note: Condition field names are editable. You can change the name if you have multiple values to compare. This makes a PHLO easier to understand.

• Drag and drop the Call forwarding component onto the canvas and connect No Match to it.

• You can choose to leave the Condition1 node empty or attach it to the Hangup component. The calls will be blocked in either case.

​

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.

​

Test

You can now make a call to your Plivo phone number from a blocked phone number or country and see that the call is rejected. If you make a call from any other number, the call should be forwarded as specified in the PHLO.

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 a Plivo XML document that screens incoming calls on a Plivo number.

How it works

Plivo requests an answer URL when it answers the call (step 2) and expects the file at that address to hold a valid XML response from the application with instructions on how to handle the call. In this example, when an incoming call is received, we check whether the number has been blacklisted. If it has, we reject the call using the Hangup XML element. If the phone number hasn’t been blacklisted, we return a Speak XML element that says, “Hello, how are you today.”

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-enabled Plivo phone number to receive incoming calls; 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 screen incoming calls

Change to the project directory and run this command to create a Rails controller to screen incoming calls.

$ rails generate controller Plivo voice

This command generates a controller named plivo_controller in the app/controllers/ directory, and a view will be generated in app/views/plivo directory. We can delete the view as we don’t need it.

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

Open the file app/controllers/plivo_controller.rb and paste this code in the PlivoController class:

include Plivo
include Plivo::XML
include Plivo::Exceptions

class PlivoController < ApplicationController
 def screen
    blacklist = ['<phone_number1>', '<phone_number2>', '<phone_number3>']

    from_number = params[:From]
    r = Response.new()
    
    if blacklist.include? from_number
        # Specify the reason for hangup
        params = {
            reason: 'rejected'
        }
        r.addHangup(params)
    else
        r.addSpeak('Hello, how are you today')
    end  
    xml = Plivo::PlivoXML.new(r)
    render xml: xml.to_xml
 end
end

Replace the phone number placeholders with actual phone numbers (for example, 12025551234).

Create a Plivo application to screen calls

Associate the Rails server 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 Screen Call. Enter the server URL you want to use (for example https://<yourdomain>.com/screen_call/) in the Answer URL field and set the method to POST. Click Create Application to save your 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 Screen Call (the name we gave the application).

Click Update Number to save.

Test

Make a call to your Plivo number using any phone. Plivo will send a request to the answer URL you provided requesting an XML response and then process the call according to the instructions in the XML document the server provides. If your phone number is not blacklisted, the call will go through and you should hear, “Hello, how are you today.”

You can create and deploy a PHLO to screen inbound calls with a few clicks on the PHLO canvas, without writing a single line of code.

​

How it works

When you receive a call on a voice-enabled Plivo number, you can control the call flow by associating a PHLO application to that Plivo number. Plivo will fetch the PHLO associated with the number and expect valid instructions via PHLO to handle the call.

​

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 calls, you must have a voice-enabled Plivo phone number. You can rent numbers from the Numbers page of the Plivo console, or by using the Numbers API.

​

Create a PHLO to block a specific number

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

You can create a PHLO to block a specific number or a whole country. This first example shows how to block a specific number.

• 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 side, drag and drop the Branch 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 Call trigger state to the Branch node.

  The branch component splits a workflow by comparing a variable with a value. Based on the conditions, the execution branches into different workflows. In this case, we compare the “from” number to a specific phone number to block.

  In the Configuration panel, enter the caller ID variable {{ "{{Start.call.from" }}}} in Variable to compare field.

  In Operation, select “Is equal to” from the drop-down list.

  In the final field, enter a value to compare: in this case a phone number — for example, 1-202-555-1234.

• The branch component has two output nodes:

  • No Match: When the values do not match
  • Condition1: When the condition matches
  Note: Condition field names are editable. You can change the name if you have multiple values to compare. This makes a PHLO easier to understand.

• Drag and drop the Call forwarding component onto the canvas and connect No Match to it.

• You can leave the Condition1 node empty or attach it to the Hangup component. The calls will be blocked in either case.

• Click Validate to save the configuration.

• Give the PHLO a name by clicking in the upper left, then click Save.

​

Create a PHLO to block a country

This example shows how to block calls from a whole country.

• 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 side, drag and drop the Branch 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 Call trigger state to the Branch node.

  The branch component splits a workflow by comparing a variable with a value. Based on the conditions, the execution branches into different workflows. In this case, we compare the two-character ISO country code to block calls from a specific country.

  In the Configuration panel, enter the ISO code variable {{ "{{Start.call.from_iso2" }}}} in Variable to compare field.

  In Operation, select “Is equal to” from the drop-down list.

  In the final field, enter a value to compare: in this case the ISO code for the country you want to block.

• The branch component has two output nodes:

  • No Match: When the values do not match
  • Condition1: When the condition matches
  Note: Condition field names are editable. You can change the name if you have multiple values to compare. This makes a PHLO easier to understand.

• Drag and drop the Call forwarding component onto the canvas and connect No Match to it.

• You can choose to leave the Condition1 node empty or attach it to the Hangup component. The calls will be blocked in either case.

​

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.

​

Test

You can now make a call to your Plivo phone number from a blocked phone number or country and see that the call is rejected. If you make a call from any other number, the call should be forwarded as specified in the PHLO.

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 a Plivo XML document that screens incoming calls on a Plivo number.

How it works

Plivo requests an answer URL when it answers the call (step 2) and expects the file at that address to hold a valid XML response from the application with instructions on how to handle the call. In this example, when an incoming call is received, we check whether the number has been blacklisted. If it has, we reject the call using the Hangup XML element. If the phone number hasn’t been blacklisted, we return a Speak XML element that says, “Hello, how are you today.”

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-enabled Plivo phone number to receive incoming calls; 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 Python development environment and a web server and safely expose that server to the internet.

Create a Flask application to screen incoming calls

Create a file called screen_call.py and paste into it this code.

from flask import Flask, Response
from flask import request
from plivo import plivoxml

app = Flask(__name__)

@app.route('/screen_call/', methods=['GET', 'POST'])
def screen_call():

    blacklist = ['<phone_number1>','<phone_number2>','<phone_number3>']
    from_number = request.values.get('From')
    response = plivoxml.ResponseElement()
    
    if from_number in blacklist:
        params = {'reason': 'rejected'}
        response.add(plivoxml.HangupElement(**params))
    else:
        response.add(plivoxml.SpeakElement('Hello, how are you today'))
    return Response(response.to_string(), mimetype='application/xml')

if __name__ == "__main__":
    app.run(host='0.0.0.0', debug=True)

Replace the phone number placeholders with actual phone numbers (for example, 12025551234).

Create a Plivo application to screen calls

Associate the Flask application 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 Screen Call. Enter the server URL you want to use (for example https://<yourdomain>.com/screen_call/) in the Answer URL field and set the method to POST. Click Create Application to save your 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 Screen Call (the name we gave the application).

Click Update Number to save.

Test

Make a call to your Plivo number using any phone. Plivo will send a request to the answer URL you provided requesting an XML response and then process the call according to the instructions in the XML document the server provides. If your phone number is not blacklisted, the call will go through and you should hear, “Hello, how are you today.”

You can create and deploy a PHLO to screen inbound calls with a few clicks on the PHLO canvas, without writing a single line of code.

​

How it works

When you receive a call on a voice-enabled Plivo number, you can control the call flow by associating a PHLO application to that Plivo number. Plivo will fetch the PHLO associated with the number and expect valid instructions via PHLO to handle the call.

​

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 calls, you must have a voice-enabled Plivo phone number. You can rent numbers from the Numbers page of the Plivo console, or by using the Numbers API.

​

Create a PHLO to block a specific number

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

You can create a PHLO to block a specific number or a whole country. This first example shows how to block a specific number.

• 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 side, drag and drop the Branch 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 Call trigger state to the Branch node.

  The branch component splits a workflow by comparing a variable with a value. Based on the conditions, the execution branches into different workflows. In this case, we compare the “from” number to a specific phone number to block.

  In the Configuration panel, enter the caller ID variable {{ "{{Start.call.from" }}}} in Variable to compare field.

  In Operation, select “Is equal to” from the drop-down list.

  In the final field, enter a value to compare: in this case a phone number — for example, 1-202-555-1234.

• The branch component has two output nodes:

  • No Match: When the values do not match
  • Condition1: When the condition matches
  Note: Condition field names are editable. You can change the name if you have multiple values to compare. This makes a PHLO easier to understand.

• Drag and drop the Call forwarding component onto the canvas and connect No Match to it.

• You can leave the Condition1 node empty or attach it to the Hangup component. The calls will be blocked in either case.

• Click Validate to save the configuration.

• Give the PHLO a name by clicking in the upper left, then click Save.

​

Create a PHLO to block a country

This example shows how to block calls from a whole country.

• 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 side, drag and drop the Branch 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 Call trigger state to the Branch node.

  The branch component splits a workflow by comparing a variable with a value. Based on the conditions, the execution branches into different workflows. In this case, we compare the two-character ISO country code to block calls from a specific country.

  In the Configuration panel, enter the ISO code variable {{ "{{Start.call.from_iso2" }}}} in Variable to compare field.

  In Operation, select “Is equal to” from the drop-down list.

  In the final field, enter a value to compare: in this case the ISO code for the country you want to block.

• The branch component has two output nodes:

  • No Match: When the values do not match
  • Condition1: When the condition matches
  Note: Condition field names are editable. You can change the name if you have multiple values to compare. This makes a PHLO easier to understand.

• Drag and drop the Call forwarding component onto the canvas and connect No Match to it.

• You can choose to leave the Condition1 node empty or attach it to the Hangup component. The calls will be blocked in either case.

​

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.

​

Test

You can now make a call to your Plivo phone number from a blocked phone number or country and see that the call is rejected. If you make a call from any other number, the call should be forwarded as specified in the PHLO.

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 a Plivo XML document that screens incoming calls on a Plivo number.

How it works

Plivo requests an answer URL when it answers the call (step 2) and expects the file at that address to hold a valid XML response from the application with instructions on how to handle the call. In this example, when an incoming call is received, we check whether the number has been blacklisted. If it has, we reject the call using the Hangup XML element. If the phone number hasn’t been blacklisted, we return a Speak XML element that says, “Hello, how are you today.”

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-enabled Plivo phone number to receive incoming calls; 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 PHP development environment and a web server and safely expose that server to the internet.

Create a Laravel controller to screen incoming calls

Change to the project directory and run this command to create a Laravel controller to screen inbound calls.

$ php artisan make:controller VoiceController

The command generates a controller named VoiceController in the app/http/controllers/ directory. Edit the app/http/controllers/voiceController.php file and paste into it this code.

<?php

namespace App\Http\Controllers;
require '../../vendor/autoload.php';
use Plivo\RestClient;
use Plivo\XML\Response;
use Illuminate\Http\Request;

class VoiceController extends Controller
{
    // Speak XML to handle your first incoming call
    public function screenCall()
    {
      $from_number = $_REQUEST['From'];
      $blacklist = array('<phone_number1>', '<phone_number2>', '<phone_number3>');
      $r = new Response();
      if (in_array($from_number, $blacklist)) {
         $params = array('reason' => 'rejected');
         $r->addHangup($params);
      } else {
         $body = "Hello, how are you today";
         $r->addSpeak($body);
      }
      Header('Content-type: text/xml');
      echo $r->toXML();
    }
}

Replace the phone number placeholders with actual phone numbers (for example, 12025551234).

Create a Plivo application to screen calls

Associate the Laravel 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 Screen Call. Enter the server URL you want to use (for example https://<yourdomain>.com/screen_call/) in the Answer URL field and set the method to POST. Click Create Application to save your 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 Screen Call (the name we gave the application).

Click Update Number to save.

Test

Make a call to your Plivo number using any phone. Plivo will send a request to the answer URL you provided requesting an XML response and then process the call according to the instructions in the XML document the server provides. If your phone number is not blacklisted, the call will go through and you should hear, “Hello, how are you today.”

You can create and deploy a PHLO to screen inbound calls with a few clicks on the PHLO canvas, without writing a single line of code.

​

How it works

When you receive a call on a voice-enabled Plivo number, you can control the call flow by associating a PHLO application to that Plivo number. Plivo will fetch the PHLO associated with the number and expect valid instructions via PHLO to handle the call.

​

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 calls, you must have a voice-enabled Plivo phone number. You can rent numbers from the Numbers page of the Plivo console, or by using the Numbers API.

​

Create a PHLO to block a specific number

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

You can create a PHLO to block a specific number or a whole country. This first example shows how to block a specific number.

• 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 side, drag and drop the Branch 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 Call trigger state to the Branch node.

  The branch component splits a workflow by comparing a variable with a value. Based on the conditions, the execution branches into different workflows. In this case, we compare the “from” number to a specific phone number to block.

  In the Configuration panel, enter the caller ID variable {{ "{{Start.call.from" }}}} in Variable to compare field.

  In Operation, select “Is equal to” from the drop-down list.

  In the final field, enter a value to compare: in this case a phone number — for example, 1-202-555-1234.

• The branch component has two output nodes:

  • No Match: When the values do not match
  • Condition1: When the condition matches
  Note: Condition field names are editable. You can change the name if you have multiple values to compare. This makes a PHLO easier to understand.

• Drag and drop the Call forwarding component onto the canvas and connect No Match to it.

• You can leave the Condition1 node empty or attach it to the Hangup component. The calls will be blocked in either case.

• Click Validate to save the configuration.

• Give the PHLO a name by clicking in the upper left, then click Save.

​

Create a PHLO to block a country

This example shows how to block calls from a whole country.

• 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 side, drag and drop the Branch 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 Call trigger state to the Branch node.

  The branch component splits a workflow by comparing a variable with a value. Based on the conditions, the execution branches into different workflows. In this case, we compare the two-character ISO country code to block calls from a specific country.

  In the Configuration panel, enter the ISO code variable {{ "{{Start.call.from_iso2" }}}} in Variable to compare field.

  In Operation, select “Is equal to” from the drop-down list.

  In the final field, enter a value to compare: in this case the ISO code for the country you want to block.

• The branch component has two output nodes:

  • No Match: When the values do not match
  • Condition1: When the condition matches
  Note: Condition field names are editable. You can change the name if you have multiple values to compare. This makes a PHLO easier to understand.

• Drag and drop the Call forwarding component onto the canvas and connect No Match to it.

• You can choose to leave the Condition1 node empty or attach it to the Hangup component. The calls will be blocked in either case.

​

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.

​

Test

You can now make a call to your Plivo phone number from a blocked phone number or country and see that the call is rejected. If you make a call from any other number, the call should be forwarded as specified in the PHLO.

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 a Plivo XML document that screens incoming calls on a Plivo number.

How it works

Plivo requests an answer URL when it answers the call (step 2) and expects the file at that address to hold a valid XML response from the application with instructions on how to handle the call. In this example, when an incoming call is received, we check whether the number has been blacklisted. If it has, we reject the call using the Hangup XML element. If the phone number hasn’t been blacklisted, we return a Speak XML element that says, “Hello, how are you today.”

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-enabled Plivo phone number to receive incoming calls; 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 screen incoming calls

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

Give the project a name — we used Screencall.

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

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

namespace Screencall.Controllers
{
    public class ScreencallController : Controller
    {
        // GET: /<controller>/
        public IActionResult Index()
        {
            string[] blacklist = { "<phone_number1>", "<phone_number2>", "<phone_number3>" };
            string fromNumber = Request.Query["From"];
            Plivo.XML.Response resp = new Plivo.XML.Response();

            if (blacklist.Equals(fromNumber))
            {
                resp.AddHangup(new Dictionary<string, string>()
            {
                {"reason","rejected"}, // Specify the reason for hangup
            });
            }
            else
            {
                resp.AddSpeak("Hello, how are you today", new Dictionary<string, string>() { });
            }
            var output = resp.ToString();
            return this.Content(output, "text/xml");
        }
    }
}

Replace the phone number placeholders with actual phone numbers (for example, 12025551234).

Create a Plivo application to screen calls

Associate the 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 Screen Call. Enter the server URL you want to use (for example https://<yourdomain>.com/screen_call/) in the Answer URL field and set the method to POST. Click Create Application to save your 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 Screen Call (the name we gave the application).

Click Update Number to save.

Test

Make a call to your Plivo number using any phone. Plivo will send a request to the answer URL you provided requesting an XML response and then process the call according to the instructions in the XML document the server provides. If your phone number is not blacklisted, the call will go through and you should hear, “Hello, how are you today.”

You can create and deploy a PHLO to screen inbound calls with a few clicks on the PHLO canvas, without writing a single line of code.

​

How it works

When you receive a call on a voice-enabled Plivo number, you can control the call flow by associating a PHLO application to that Plivo number. Plivo will fetch the PHLO associated with the number and expect valid instructions via PHLO to handle the call.

​

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 calls, you must have a voice-enabled Plivo phone number. You can rent numbers from the Numbers page of the Plivo console, or by using the Numbers API.

​

Create a PHLO to block a specific number

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

You can create a PHLO to block a specific number or a whole country. This first example shows how to block a specific number.

• 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 side, drag and drop the Branch 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 Call trigger state to the Branch node.

  The branch component splits a workflow by comparing a variable with a value. Based on the conditions, the execution branches into different workflows. In this case, we compare the “from” number to a specific phone number to block.

  In the Configuration panel, enter the caller ID variable {{ "{{Start.call.from" }}}} in Variable to compare field.

  In Operation, select “Is equal to” from the drop-down list.

  In the final field, enter a value to compare: in this case a phone number — for example, 1-202-555-1234.

• The branch component has two output nodes:

  • No Match: When the values do not match
  • Condition1: When the condition matches
  Note: Condition field names are editable. You can change the name if you have multiple values to compare. This makes a PHLO easier to understand.

• Drag and drop the Call forwarding component onto the canvas and connect No Match to it.

• You can leave the Condition1 node empty or attach it to the Hangup component. The calls will be blocked in either case.

• Click Validate to save the configuration.

• Give the PHLO a name by clicking in the upper left, then click Save.

​

Create a PHLO to block a country

This example shows how to block calls from a whole country.

• 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 side, drag and drop the Branch 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 Call trigger state to the Branch node.

  The branch component splits a workflow by comparing a variable with a value. Based on the conditions, the execution branches into different workflows. In this case, we compare the two-character ISO country code to block calls from a specific country.

  In the Configuration panel, enter the ISO code variable {{ "{{Start.call.from_iso2" }}}} in Variable to compare field.

  In Operation, select “Is equal to” from the drop-down list.

  In the final field, enter a value to compare: in this case the ISO code for the country you want to block.

• The branch component has two output nodes:

  • No Match: When the values do not match
  • Condition1: When the condition matches
  Note: Condition field names are editable. You can change the name if you have multiple values to compare. This makes a PHLO easier to understand.

• Drag and drop the Call forwarding component onto the canvas and connect No Match to it.

• You can choose to leave the Condition1 node empty or attach it to the Hangup component. The calls will be blocked in either case.

​

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.

​

Test

You can now make a call to your Plivo phone number from a blocked phone number or country and see that the call is rejected. If you make a call from any other number, the call should be forwarded as specified in the PHLO.

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 a Plivo XML document that screens incoming calls on a Plivo number.

How it works

Plivo requests an answer URL when it answers the call (step 2) and expects the file at that address to hold a valid XML response from the application with instructions on how to handle the call. In this example, when an incoming call is received, we check whether the number has been blacklisted. If it has, we reject the call using the Hangup XML element. If the phone number hasn’t been blacklisted, we return a Speak XML element that says, “Hello, how are you today.”

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-enabled Plivo phone number to receive incoming calls; 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 Java development environment and a web server and safely expose that server to the internet.

Create a Spark application to screen incoming calls

Create a Java class named ScreenCall and paste into it this code.

import java.util.Arrays;
import com.plivo.api.xml.Hangup;
import com.plivo.api.xml.Response;
import com.plivo.api.xml.Speak;
import static spark.Spark.*;

public class screencalls {
    public static void main(String[] args) {
        post("/screen_call/", (request, response) -> {
            response.type("application/xml");
            String fromNumber = request.queryParams("From");
            String[] blacklist = { "<phone_number1>","<phone_number2>", "<phone_number3>"};
        if (Arrays.asList(blacklist).contains(fromNumber)) {
            return new Response()
                    .children(
                            new Hangup()
                                    .reason("rejected")
                    ).toXmlString();
        } else {
            return new Response()
                    .children(
                            new Speak("Hello, how are you today")
                    ).toXmlString();
        }
        });
    }
}

Replace the phone number placeholders with actual phone numbers (for example, 12025551234).

Create a Plivo application to screen calls

Associate the Spark application 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 Screen Call. Enter the server URL you want to use (for example https://<yourdomain>.com/screen_call/) in the Answer URL field and set the method to POST. Click Create Application to save your 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 Screen Call (the name we gave the application).

Click Update Number to save.

Test

Make a call to your Plivo number using any phone. Plivo will send a request to the answer URL you provided requesting an XML response and then process the call according to the instructions in the XML document the server provides. If your phone number is not blacklisted, the call will go through and you should hear, “Hello, how are you today.”

You can create and deploy a PHLO to screen inbound calls with a few clicks on the PHLO canvas, without writing a single line of code.

​

How it works

When you receive a call on a voice-enabled Plivo number, you can control the call flow by associating a PHLO application to that Plivo number. Plivo will fetch the PHLO associated with the number and expect valid instructions via PHLO to handle the call.

​

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 calls, you must have a voice-enabled Plivo phone number. You can rent numbers from the Numbers page of the Plivo console, or by using the Numbers API.

​

Create a PHLO to block a specific number

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

You can create a PHLO to block a specific number or a whole country. This first example shows how to block a specific number.

• 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 side, drag and drop the Branch 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 Call trigger state to the Branch node.

  The branch component splits a workflow by comparing a variable with a value. Based on the conditions, the execution branches into different workflows. In this case, we compare the “from” number to a specific phone number to block.

  In the Configuration panel, enter the caller ID variable {{ "{{Start.call.from" }}}} in Variable to compare field.

  In Operation, select “Is equal to” from the drop-down list.

  In the final field, enter a value to compare: in this case a phone number — for example, 1-202-555-1234.

• The branch component has two output nodes:

  • No Match: When the values do not match
  • Condition1: When the condition matches
  Note: Condition field names are editable. You can change the name if you have multiple values to compare. This makes a PHLO easier to understand.

• Drag and drop the Call forwarding component onto the canvas and connect No Match to it.

• You can leave the Condition1 node empty or attach it to the Hangup component. The calls will be blocked in either case.

• Click Validate to save the configuration.

• Give the PHLO a name by clicking in the upper left, then click Save.

​

Create a PHLO to block a country

This example shows how to block calls from a whole country.

• 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 side, drag and drop the Branch 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 Call trigger state to the Branch node.

  The branch component splits a workflow by comparing a variable with a value. Based on the conditions, the execution branches into different workflows. In this case, we compare the two-character ISO country code to block calls from a specific country.

  In the Configuration panel, enter the ISO code variable {{ "{{Start.call.from_iso2" }}}} in Variable to compare field.

  In Operation, select “Is equal to” from the drop-down list.

  In the final field, enter a value to compare: in this case the ISO code for the country you want to block.

• The branch component has two output nodes:

  • No Match: When the values do not match
  • Condition1: When the condition matches
  Note: Condition field names are editable. You can change the name if you have multiple values to compare. This makes a PHLO easier to understand.

• Drag and drop the Call forwarding component onto the canvas and connect No Match to it.

• You can choose to leave the Condition1 node empty or attach it to the Hangup component. The calls will be blocked in either case.

​

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.

​

Test

You can now make a call to your Plivo phone number from a blocked phone number or country and see that the call is rejected. If you make a call from any other number, the call should be forwarded as specified in the PHLO.

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 a Plivo XML document that screens incoming calls on a Plivo number.

How it works

Plivo requests an answer URL when it answers the call (step 2) and expects the file at that address to hold a valid XML response from the application with instructions on how to handle the call. In this example, when an incoming call is received, we check whether the number has been blacklisted. If it has, we reject the call using the Hangup XML element. If the phone number hasn’t been blacklisted, we return a Speak XML element that says, “Hello, how are you today.”

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-enabled Plivo phone number to receive incoming calls; 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 Go development environment and a web server and safely expose that server to the internet.

Create a Go server to screen incoming calls

Create a file called screen_call.go and paste into it this code.

package main

import (
	"github.com/go-martini/martini"
	"github.com/plivo/plivo-go/v7/xml"
	"net/http"
)

func main() {
	m := martini.Classic()
	m.Get("/screen_call", func(w http.ResponseWriter, r *http.Request) string {
		w.Header().Set("Content-Type", "application/xml")
		fromNumber := r.FormValue("From")                                  
		blacklist := []string{"<phone_number1>", "<phone_number2>", "<phone_number3>"}

​		for _, num := range blacklist {
​			if num == fromNumber {
​				return xml.ResponseElement{
​					Contents: []interface{}{
​						new(xml.HangupElement).
​							SetReason("rejected"),
​					},
​				}.String()
​			}
​		}
​		return xml.ResponseElement{Contents: []interface{}{
​			new(xml.SpeakElement).
​				SetLoop(0).
​				AddSpeak("Hello, how are you today"),
​		}}.String()
​	})
​	m.Run()
}

Replace the phone number placeholders with actual phone numbers (for example, 12025551234).

Create a Plivo application to screen calls

Associate the Go application 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 Screen Call. Enter the server URL you want to use (for example https://<yourdomain>.com/screen_call/) in the Answer URL field and set the method to POST. Click Create Application to save your 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 Screen Call (the name we gave the application).

Click Update Number to save.

Test

Make a call to your Plivo number using any phone. Plivo will send a request to the answer URL you provided requesting an XML response and then process the call according to the instructions in the XML document the server provides. If your phone number is not blacklisted, the call will go through and you should hear, “Hello, how are you today.”