> ## Documentation Index > Fetch the complete documentation index at: https://plivo.com/docs/llms.txt > Use this file to discover all available pages before exploring further. # Screen Incoming Calls > Block calls from specific phone numbers or country codes ## Overview When you don’t want to receive calls from a specific phone number or even a whole country, follow the instructions in this guide to create an application to block phone numbers or country codes associated with incoming calls. You can screen incoming calls either by using our PHLO visual workflow builder or our APIs and XML documents. Follow the instructions in one of the tabs below. Here’s how to use a Plivo XML document that screens incoming calls on a Plivo number. ## How it works Inbound Call Flow 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](/voice/xml/hangup/) XML element. If the phone number hasn't been blacklisted, we return a [Speak](/voice/xml/speak/) XML element that says, “Hello, how are you today.” ## Prerequisites To get started, you need a Plivo account — [sign up](https://cx.plivo.com/signup) 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](https://cx.plivo.com/phone-numbers) page of the Plivo console, or by using the [Numbers API](/numbers/). If this is your first time using Plivo APIs, follow our instructions to [set up a Node.js development environment](/sdk/server/set-up-node-dev-environment-api-xml-voice/) 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. ```js theme={null} 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 = [ '', '', '']; // 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](https://cx.plivo.com/xml-applications) in the Plivo console and click on **Add New Application**, or use Plivo’s [Application API](/account/api/application/#create-an-application). Give your application a name — we called ours `Screen Call`. Enter the server URL you want to use (for example `https://.com/screen_call/`) in the `Answer URL` field and set the method to `POST`. Click **Create Application** to save your application. Create Screencall Application ## Assign a Plivo number to your application Navigate to the [Numbers](https://cx.plivo.com/phone-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. Assign Screen call Application ## 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.” ## Overview When you don’t want to receive calls from a specific phone number or even a whole country, follow the instructions in this guide to create an application to block phone numbers or country codes associated with incoming calls. You can screen incoming calls either by using our PHLO visual workflow builder or our APIs and XML documents. Follow the instructions in one of the tabs below. Here’s how to use a Plivo XML document that screens incoming calls on a Plivo number. ## How it works Inbound Call Flow 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](/voice/xml/hangup/) XML element. If the phone number hasn't been blacklisted, we return a [Speak](/voice/xml/speak/) XML element that says, “Hello, how are you today.” ## Prerequisites To get started, you need a Plivo account — [sign up](https://cx.plivo.com/signup) 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](https://cx.plivo.com/phone-numbers) page of the Plivo console, or by using the [Numbers API](/numbers/). If this is your first time using Plivo APIs, follow our instructions to [set up a Ruby development environment](/sdk/server/set-up-ruby-dev-environment-api-xml-voice/) 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. ```shell theme={null} $ 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. ```shell theme={null} $ rm app/views/plivo/voice.html.erb ``` Open the file app/controllers/plivo\_controller.rb and paste this code in the PlivoController class: ```rb theme={null} include Plivo include Plivo::XML include Plivo::Exceptions class PlivoController < ApplicationController def screen blacklist = ['', '', ''] 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](https://cx.plivo.com/xml-applications) in the Plivo console and click on **Add New Application**, or use Plivo’s [Application API](/account/api/application/#create-an-application). Give your application a name — we called ours `Screen Call`. Enter the server URL you want to use (for example `https://.com/screen_call/`) in the `Answer URL` field and set the method to `POST`. Click **Create Application** to save your application. Create Screencall Application ## Assign a Plivo number to your application Navigate to the [Numbers](https://cx.plivo.com/phone-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. Assign Screen call Application ## 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.” ## Overview When you don’t want to receive calls from a specific phone number or even a whole country, follow the instructions in this guide to create an application to block phone numbers or country codes associated with incoming calls. You can screen incoming calls either by using our PHLO visual workflow builder or our APIs and XML documents. Follow the instructions in one of the tabs below. Here’s how to use a Plivo XML document that screens incoming calls on a Plivo number. ## How it works Inbound Call Flow 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](/voice/xml/hangup/) XML element. If the phone number hasn't been blacklisted, we return a [Speak](/voice/xml/speak/) XML element that says, “Hello, how are you today.” ## Prerequisites To get started, you need a Plivo account — [sign up](https://cx.plivo.com/signup) 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](https://cx.plivo.com/phone-numbers) page of the Plivo console, or by using the [Numbers API](/numbers/). If this is your first time using Plivo APIs, follow our instructions to [set up a Python development environment](/sdk/server/set-up-python-dev-environment-api-xml-voice/) 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. ```py theme={null} 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 = ['','',''] 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](https://cx.plivo.com/xml-applications) in the Plivo console and click on **Add New Application**, or use Plivo’s [Application API](/account/api/application/#create-an-application). Give your application a name — we called ours `Screen Call`. Enter the server URL you want to use (for example `https://.com/screen_call/`) in the `Answer URL` field and set the method to `POST`. Click **Create Application** to save your application. Create Screencall Application ## Assign a Plivo number to your application Navigate to the [Numbers](https://cx.plivo.com/phone-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. Assign Screen call Application ## 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.” ## Overview When you don’t want to receive calls from a specific phone number or even a whole country, follow the instructions in this guide to create an application to block phone numbers or country codes associated with incoming calls. You can screen incoming calls either by using our PHLO visual workflow builder or our APIs and XML documents. Follow the instructions in one of the tabs below. Here’s how to use a Plivo XML document that screens incoming calls on a Plivo number. ## How it works Inbound Call Flow 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](/voice/xml/hangup/) XML element. If the phone number hasn't been blacklisted, we return a [Speak](/voice/xml/speak/) XML element that says, “Hello, how are you today.” ## Prerequisites To get started, you need a Plivo account — [sign up](https://cx.plivo.com/signup) 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](https://cx.plivo.com/phone-numbers) page of the Plivo console, or by using the [Numbers API](/numbers/). If this is your first time using Plivo APIs, follow our instructions to [set up a PHP development environment](/sdk/server/set-up-php-dev-environment-api-xml-voice/) 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. ```shell theme={null} $ 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 theme={null} ', '', ''); $r = new Response(); if (in_array($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](https://cx.plivo.com/xml-applications) in the Plivo console and click on **Add New Application**, or use Plivo’s [Application API](/account/api/application/#create-an-application). Give your application a name — we called ours `Screen Call`. Enter the server URL you want to use (for example `https://.com/screen_call/`) in the `Answer URL` field and set the method to `POST`. Click **Create Application** to save your application. Create Screencall Application ## Assign a Plivo number to your application Navigate to the [Numbers](https://cx.plivo.com/phone-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. Assign Screen call Application ## 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.” ## Overview When you don’t want to receive calls from a specific phone number or even a whole country, follow the instructions in this guide to create an application to block phone numbers or country codes associated with incoming calls. You can screen incoming calls either by using our PHLO visual workflow builder or our APIs and XML documents. Follow the instructions in one of the tabs below. Here’s how to use a Plivo XML document that screens incoming calls on a Plivo number. ## How it works Inbound Call Flow 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](/voice/xml/hangup/) XML element. If the phone number hasn't been blacklisted, we return a [Speak](/voice/xml/speak/) XML element that says, “Hello, how are you today.” ## Prerequisites To get started, you need a Plivo account — [sign up](https://cx.plivo.com/signup) 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](https://cx.plivo.com/phone-numbers) page of the Plivo console, or by using the [Numbers API](/numbers/). If this is your first time using Plivo APIs, follow our instructions to [set up a .NET development environment](/sdk/server/set-up-dotnet-dev-environment-api-xml-voice/) 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). Create an MVC app 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. ```cs theme={null} using System; using System.Collections.Generic; using Plivo.XML; using Microsoft.AspNetCore.Mvc; namespace Screencall.Controllers { public class ScreencallController : Controller { // GET: // public IActionResult Index() { string[] blacklist = { "", "", "" }; string fromNumber = Request.Query["From"]; Plivo.XML.Response resp = new Plivo.XML.Response(); if (blacklist.Equals(fromNumber)) { resp.AddHangup(new Dictionary() { {"reason","rejected"}, // Specify the reason for hangup }); } else { resp.AddSpeak("Hello, how are you today", new Dictionary() { }); } 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](https://cx.plivo.com/xml-applications) in the Plivo console and click on **Add New Application**, or use Plivo’s [Application API](/account/api/application/#create-an-application). Give your application a name — we called ours `Screen Call`. Enter the server URL you want to use (for example `https://.com/screen_call/`) in the `Answer URL` field and set the method to `POST`. Click **Create Application** to save your application. Create Screencall Application ## Assign a Plivo number to your application Navigate to the [Numbers](https://cx.plivo.com/phone-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. Assign Screen call Application ## 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.” ## Overview When you don’t want to receive calls from a specific phone number or even a whole country, follow the instructions in this guide to create an application to block phone numbers or country codes associated with incoming calls. You can screen incoming calls either by using our PHLO visual workflow builder or our APIs and XML documents. Follow the instructions in one of the tabs below. Here’s how to use a Plivo XML document that screens incoming calls on a Plivo number. ## How it works Inbound Call Flow 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](/voice/xml/hangup/) XML element. If the phone number hasn't been blacklisted, we return a [Speak](/voice/xml/speak/) XML element that says, “Hello, how are you today.” ## Prerequisites To get started, you need a Plivo account — [sign up](https://cx.plivo.com/signup) 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](https://cx.plivo.com/phone-numbers) page of the Plivo console, or by using the [Numbers API](/numbers/). If this is your first time using Plivo APIs, follow our instructions to [set up a Java development environment](/sdk/server/set-up-java-dev-environment-api-xml-voice/) 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. ```java theme={null} 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 = { "","", ""}; 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](https://cx.plivo.com/xml-applications) in the Plivo console and click on **Add New Application**, or use Plivo’s [Application API](/account/api/application/#create-an-application). Give your application a name — we called ours `Screen Call`. Enter the server URL you want to use (for example `https://.com/screen_call/`) in the `Answer URL` field and set the method to `POST`. Click **Create Application** to save your application. Create Screencall Application ## Assign a Plivo number to your application Navigate to the [Numbers](https://cx.plivo.com/phone-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. Assign Screen call Application ## 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.” ## Overview When you don’t want to receive calls from a specific phone number or even a whole country, follow the instructions in this guide to create an application to block phone numbers or country codes associated with incoming calls. You can screen incoming calls either by using our PHLO visual workflow builder or our APIs and XML documents. Follow the instructions in one of the tabs below. Here’s how to use a Plivo XML document that screens incoming calls on a Plivo number. ## How it works Inbound Call Flow 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](/voice/xml/hangup/) XML element. If the phone number hasn't been blacklisted, we return a [Speak](/voice/xml/speak/) XML element that says, “Hello, how are you today.” ## Prerequisites To get started, you need a Plivo account — [sign up](https://cx.plivo.com/signup) 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](https://cx.plivo.com/phone-numbers) page of the Plivo console, or by using the [Numbers API](/numbers/). If this is your first time using Plivo APIs, follow our instructions to [set up a Go development environment](/sdk/server/set-up-go-dev-environment-api-xml-voice/) 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. ```go theme={null} 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{"", "", ""} ​ 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](https://cx.plivo.com/xml-applications) in the Plivo console and click on **Add New Application**, or use Plivo’s [Application API](/account/api/application/#create-an-application). Give your application a name — we called ours `Screen Call`. Enter the server URL you want to use (for example `https://.com/screen_call/`) in the `Answer URL` field and set the method to `POST`. Click **Create Application** to save your application. Create Screencall Application ## Assign a Plivo number to your application Navigate to the [Numbers](https://cx.plivo.com/phone-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. Assign Screen call Application ## 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.”