diff --git a/src/application/config/migration.php b/src/application/config/migration.php
index 988cc798..b60a960f 100755
--- a/src/application/config/migration.php
+++ b/src/application/config/migration.php
@@ -37,7 +37,7 @@ $config['migration_table'] = 'ea_migrations';
 | be upgraded / downgraded to.
 |
 */
-$config['migration_version'] = 14; // current
+$config['migration_version'] = 15; // current
 
 
 /*
diff --git a/src/application/controllers/Appointments.php b/src/application/controllers/Appointments.php
index 225bfb9f..3d6a44d9 100755
--- a/src/application/controllers/Appointments.php
+++ b/src/application/controllers/Appointments.php
@@ -77,6 +77,7 @@ class Appointments extends CI_Controller {
             $date_format = $this->settings_model->get_setting('date_format');
             $time_format = $this->settings_model->get_setting('time_format');
             $first_weekday = $this->settings_model->get_setting('first_weekday');
+            $require_phone_number = $this->settings_model->get_setting('require_phone_number');
             $display_cookie_notice = $this->settings_model->get_setting('display_cookie_notice');
             $cookie_notice_content = $this->settings_model->get_setting('cookie_notice_content');
             $display_terms_and_conditions = $this->settings_model->get_setting('display_terms_and_conditions');
@@ -149,6 +150,7 @@ class Appointments extends CI_Controller {
                 'date_format' => $date_format,
                 'time_format' => $time_format,
                 'first_weekday' => $first_weekday,
+                'require_phone_number' => $require_phone_number,
                 'appointment_data' => $appointment,
                 'provider_data' => $provider,
                 'customer_data' => $customer,
diff --git a/src/application/controllers/Backend.php b/src/application/controllers/Backend.php
index b649a131..e1624254 100755
--- a/src/application/controllers/Backend.php
+++ b/src/application/controllers/Backend.php
@@ -135,6 +135,7 @@ class Backend extends CI_Controller {
         $view['date_format'] = $this->settings_model->get_setting('date_format');
         $view['time_format'] = $this->settings_model->get_setting('time_format');
         $view['first_weekday'] = $this->settings_model->get_setting('first_weekday');
+        $view['require_phone_number'] = $this->settings_model->get_setting('require_phone_number');
         $view['customers'] = $this->customers_model->get_batch();
         $view['available_providers'] = $this->providers_model->get_available_providers();
         $view['available_services'] = $this->services_model->get_available_services();
diff --git a/src/application/language/arabic/translations_lang.php b/src/application/language/arabic/translations_lang.php
index 0cf5406b..b6592f91 100755
--- a/src/application/language/arabic/translations_lang.php
+++ b/src/application/language/arabic/translations_lang.php
@@ -305,3 +305,5 @@ $lang['new_extra_period_title'] = '';
 $lang['extra_period_saved'] = '';
 $lang['add_extra_periods_during_each_day'] = '';
 $lang['add_extra_period'] = '';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
diff --git a/src/application/language/bulgarian/translations_lang.php b/src/application/language/bulgarian/translations_lang.php
index 8b95baf5..ddc60363 100755
--- a/src/application/language/bulgarian/translations_lang.php
+++ b/src/application/language/bulgarian/translations_lang.php
@@ -305,3 +305,5 @@ $lang['new_extra_period_title'] = '';
 $lang['extra_period_saved'] = '';
 $lang['add_extra_periods_during_each_day'] = '';
 $lang['add_extra_period'] = '';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
diff --git a/src/application/language/chinese/translations_lang.php b/src/application/language/chinese/translations_lang.php
index b3f9f0d8..268173d2 100755
--- a/src/application/language/chinese/translations_lang.php
+++ b/src/application/language/chinese/translations_lang.php
@@ -305,3 +305,5 @@ $lang['new_extra_period_title'] = '';
 $lang['extra_period_saved'] = '';
 $lang['add_extra_periods_during_each_day'] = '';
 $lang['add_extra_period'] = '';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
diff --git a/src/application/language/danish/translations_lang.php b/src/application/language/danish/translations_lang.php
index 7b901701..170057b3 100755
--- a/src/application/language/danish/translations_lang.php
+++ b/src/application/language/danish/translations_lang.php
@@ -305,3 +305,5 @@ $lang['new_extra_period_title'] = '';
 $lang['extra_period_saved'] = '';
 $lang['add_extra_periods_during_each_day'] = '';
 $lang['add_extra_period'] = '';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
diff --git a/src/application/language/dutch/translations_lang.php b/src/application/language/dutch/translations_lang.php
index d02bd3ad..316760d5 100755
--- a/src/application/language/dutch/translations_lang.php
+++ b/src/application/language/dutch/translations_lang.php
@@ -305,3 +305,5 @@ $lang['new_extra_period_title'] = '';
 $lang['extra_period_saved'] = '';
 $lang['add_extra_periods_during_each_day'] = '';
 $lang['add_extra_period'] = '';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
diff --git a/src/application/language/english/translations_lang.php b/src/application/language/english/translations_lang.php
index 3aa67d2c..eab10493 100755
--- a/src/application/language/english/translations_lang.php
+++ b/src/application/language/english/translations_lang.php
@@ -305,3 +305,5 @@ $lang['new_extra_period_title'] = 'New working day';
 $lang['extra_period_saved'] = 'New working day saved successfully!';
 $lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
 $lang['add_extra_period'] = 'Add a working day';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
diff --git a/src/application/language/finnish/translations_lang.php b/src/application/language/finnish/translations_lang.php
index a0763798..ada208ba 100755
--- a/src/application/language/finnish/translations_lang.php
+++ b/src/application/language/finnish/translations_lang.php
@@ -305,3 +305,5 @@ $lang['new_extra_period_title'] = '';
 $lang['extra_period_saved'] = '';
 $lang['add_extra_periods_during_each_day'] = '';
 $lang['add_extra_period'] = '';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
diff --git a/src/application/language/french/translations_lang.php b/src/application/language/french/translations_lang.php
index 22301b3d..29dcfdf1 100755
--- a/src/application/language/french/translations_lang.php
+++ b/src/application/language/french/translations_lang.php
@@ -308,3 +308,5 @@ $lang['new_extra_period_title'] = '';
 $lang['extra_period_saved'] = '';
 $lang['add_extra_periods_during_each_day'] = '';
 $lang['add_extra_period'] = '';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
diff --git a/src/application/language/german/translations_lang.php b/src/application/language/german/translations_lang.php
index ba7ae975..77f675ae 100755
--- a/src/application/language/german/translations_lang.php
+++ b/src/application/language/german/translations_lang.php
@@ -305,3 +305,5 @@ $lang['new_extra_period_title'] = '';
 $lang['extra_period_saved'] = '';
 $lang['add_extra_periods_during_each_day'] = '';
 $lang['add_extra_period'] = '';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
diff --git a/src/application/language/greek/translations_lang.php b/src/application/language/greek/translations_lang.php
index 3201e7c3..77027506 100755
--- a/src/application/language/greek/translations_lang.php
+++ b/src/application/language/greek/translations_lang.php
@@ -305,3 +305,6 @@ $lang['new_extra_period_title'] = '';
 $lang['extra_period_saved'] = '';
 $lang['add_extra_periods_during_each_day'] = '';
 $lang['add_extra_period'] = '';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
+
diff --git a/src/application/language/hindi/translations_lang.php b/src/application/language/hindi/translations_lang.php
index a83722e0..95332ef7 100755
--- a/src/application/language/hindi/translations_lang.php
+++ b/src/application/language/hindi/translations_lang.php
@@ -305,3 +305,5 @@ $lang['new_extra_period_title'] = '';
 $lang['extra_period_saved'] = '';
 $lang['add_extra_periods_during_each_day'] = '';
 $lang['add_extra_period'] = '';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
diff --git a/src/application/language/hungarian/translations_lang.php b/src/application/language/hungarian/translations_lang.php
index 59112c9a..7e695326 100755
--- a/src/application/language/hungarian/translations_lang.php
+++ b/src/application/language/hungarian/translations_lang.php
@@ -305,3 +305,5 @@ $lang['new_extra_period_title'] = '';
 $lang['extra_period_saved'] = '';
 $lang['add_extra_periods_during_each_day'] = '';
 $lang['add_extra_period'] = '';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
diff --git a/src/application/language/japanese/translations_lang.php b/src/application/language/japanese/translations_lang.php
index ad7eef49..0e520228 100755
--- a/src/application/language/japanese/translations_lang.php
+++ b/src/application/language/japanese/translations_lang.php
@@ -305,3 +305,5 @@ $lang['new_extra_period_title'] = '';
 $lang['extra_period_saved'] = '';
 $lang['add_extra_periods_during_each_day'] = '';
 $lang['add_extra_period'] = '';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
diff --git a/src/application/language/luxembourgish/translations_lang.php b/src/application/language/luxembourgish/translations_lang.php
index 9fb93532..3d53f965 100755
--- a/src/application/language/luxembourgish/translations_lang.php
+++ b/src/application/language/luxembourgish/translations_lang.php
@@ -305,3 +305,5 @@ $lang['new_extra_period_title'] = '';
 $lang['extra_period_saved'] = '';
 $lang['add_extra_periods_during_each_day'] = '';
 $lang['add_extra_period'] = '';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
diff --git a/src/application/language/polish/translations_lang.php b/src/application/language/polish/translations_lang.php
index 813642c4..34d59f13 100755
--- a/src/application/language/polish/translations_lang.php
+++ b/src/application/language/polish/translations_lang.php
@@ -305,3 +305,5 @@ $lang['new_extra_period_title'] = '';
 $lang['extra_period_saved'] = '';
 $lang['add_extra_periods_during_each_day'] = '';
 $lang['add_extra_period'] = '';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
diff --git a/src/application/language/portuguese-br/translations_lang.php b/src/application/language/portuguese-br/translations_lang.php
index fee45f3f..48e6a57e 100755
--- a/src/application/language/portuguese-br/translations_lang.php
+++ b/src/application/language/portuguese-br/translations_lang.php
@@ -298,9 +298,6 @@ $lang['delete_personal_information_hint'] = 'Deletar toda informação pessoal d
 $lang['delete_personal_information'] = 'Deletar Informação Pessoal';
 $lang['delete_personal_information_prompt'] = 'Tem certeza que deja deletar suas informações pessoais? Essa ação não pode ser desfeita.';
 $lang['location'] = 'Location';
-$lang['availabilities_type'] = 'Availabilities Type';
-$lang['flexible'] = 'Flexible';
-$lang['fixed'] = 'Fixed';
 $lang['extra_period'] = '';
 $lang['extra_periods'] = '';
 $lang['extra_periods_hint'] = '';
@@ -310,3 +307,5 @@ $lang['add_extra_periods_during_each_day'] = '';
 $lang['add_extra_period'] = '';
 $lang['first_weekday'] = 'First day of week';
 $lang['first_weekday_hint'] = 'Set the first day of the calendar week.';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
diff --git a/src/application/language/portuguese/translations_lang.php b/src/application/language/portuguese/translations_lang.php
index dc27b027..76e6f3f3 100755
--- a/src/application/language/portuguese/translations_lang.php
+++ b/src/application/language/portuguese/translations_lang.php
@@ -305,3 +305,5 @@ $lang['new_extra_period_title'] = '';
 $lang['extra_period_saved'] = '';
 $lang['add_extra_periods_during_each_day'] = '';
 $lang['add_extra_period'] = '';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
diff --git a/src/application/language/romanian/translations_lang.php b/src/application/language/romanian/translations_lang.php
index 2c77ccbd..e26dbb12 100755
--- a/src/application/language/romanian/translations_lang.php
+++ b/src/application/language/romanian/translations_lang.php
@@ -305,3 +305,5 @@ $lang['new_extra_period_title'] = '';
 $lang['extra_period_saved'] = '';
 $lang['add_extra_periods_during_each_day'] = '';
 $lang['add_extra_period'] = '';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
diff --git a/src/application/language/russian/translations_lang.php b/src/application/language/russian/translations_lang.php
index d9c2130a..01c62df2 100755
--- a/src/application/language/russian/translations_lang.php
+++ b/src/application/language/russian/translations_lang.php
@@ -305,3 +305,5 @@ $lang['new_extra_period_title'] = '';
 $lang['extra_period_saved'] = '';
 $lang['add_extra_periods_during_each_day'] = '';
 $lang['add_extra_period'] = '';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
diff --git a/src/application/language/slovak/translations_lang.php b/src/application/language/slovak/translations_lang.php
index 83a3538f..ebf32248 100755
--- a/src/application/language/slovak/translations_lang.php
+++ b/src/application/language/slovak/translations_lang.php
@@ -305,3 +305,5 @@ $lang['new_extra_period_title'] = '';
 $lang['extra_period_saved'] = '';
 $lang['add_extra_periods_during_each_day'] = '';
 $lang['add_extra_period'] = '';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
diff --git a/src/application/language/spanish/translations_lang.php b/src/application/language/spanish/translations_lang.php
index 07d0cf50..4525e288 100755
--- a/src/application/language/spanish/translations_lang.php
+++ b/src/application/language/spanish/translations_lang.php
@@ -305,3 +305,5 @@ $lang['new_extra_period_title'] = '';
 $lang['extra_period_saved'] = '';
 $lang['add_extra_periods_during_each_day'] = '';
 $lang['add_extra_period'] = '';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
diff --git a/src/application/language/turkish/translations_lang.php b/src/application/language/turkish/translations_lang.php
index 429416f2..d65fe990 100755
--- a/src/application/language/turkish/translations_lang.php
+++ b/src/application/language/turkish/translations_lang.php
@@ -305,3 +305,5 @@ $lang['new_extra_period_title'] = '';
 $lang['extra_period_saved'] = '';
 $lang['add_extra_periods_during_each_day'] = '';
 $lang['add_extra_period'] = '';
+$lang['require_phone_number'] = 'Require phone number';
+$lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
diff --git a/src/application/migrations/015_add_require_phone_number_setting.php b/src/application/migrations/015_add_require_phone_number_setting.php
new file mode 100644
index 00000000..c0753df4
--- /dev/null
+++ b/src/application/migrations/015_add_require_phone_number_setting.php
@@ -0,0 +1,35 @@
+<?php defined('BASEPATH') OR exit('No direct script access allowed');
+
+/* ----------------------------------------------------------------------------
+ * Easy!Appointments - Open Source Web Scheduler
+ *
+ * @package     EasyAppointments
+ * @author      A.Tselegidis <alextselegidis@gmail.com>
+ * @copyright   Copyright (c) 2013 - 2018, Alex Tselegidis
+ * @license     http://opensource.org/licenses/GPL-3.0 - GPLv3
+ * @link        http://easyappointments.org
+ * @since       v1.4.0
+ * ---------------------------------------------------------------------------- */
+
+class Migration_Add_require_phone_number_setting extends CI_Migration {
+    public function up()
+    {
+        $this->load->model('settings_model');
+
+        try
+        {
+            $this->settings_model->get_setting('require_phone_number');
+        }
+        catch (Exception $exception)
+        {
+            $this->settings_model->set_setting('require_phone_number', '1');
+        }
+    }
+
+    public function down()
+    {
+        $this->load->model('settings_model');
+
+        $this->settings_model->remove_setting('require_phone_number');
+    }
+}
diff --git a/src/application/models/Customers_model.php b/src/application/models/Customers_model.php
index b949df60..e6cb88ac 100644
--- a/src/application/models/Customers_model.php
+++ b/src/application/models/Customers_model.php
@@ -211,10 +211,14 @@ class Customers_Model extends CI_Model {
                     . 'exist in the database.');
             }
         }
+
+        $query = $this->db->get_where('ea_settings', ['name' => 'require_phone_number']);
+        $phone_number_required = $query->num_rows() > 0 ? $query->row() === '1' : false;
+
         // Validate required fields
         if ( ! isset($customer['last_name'])
             || ! isset($customer['email'])
-            || ! isset($customer['phone_number']))
+            || (!isset($customer['phone_number']) && $phone_number_required))
         {
             throw new Exception('Not all required fields are provided: '
                 . print_r($customer, TRUE));
diff --git a/src/application/views/appointments/book.php b/src/application/views/appointments/book.php
index 04daa75f..bf606c52 100755
--- a/src/application/views/appointments/book.php
+++ b/src/application/views/appointments/book.php
@@ -223,8 +223,10 @@
                                     <input type="text" id="email" class="required form-control" maxlength="120" />
                                 </div>
                                 <div class="form-group">
-                                    <label for="phone-number" class="control-label"><?= lang('phone_number') ?> *</label>
-                                    <input type="text" id="phone-number" class="required form-control" maxlength="60" />
+                                    <label for="phone-number" class="control-label"><?= lang('phone_number') ?>
+                                        <?php echo ('1' === $require_phone_number) ? '*' : ''; ?></label>
+                                    <input type="text" id="phone-number" class="<?php echo ('1' === $require_phone_number) ? 'required' : ''; ?>
+                                        form-control" maxlength="60" />
                                 </div>
                             </div>
 
diff --git a/src/application/views/backend/customers.php b/src/application/views/backend/customers.php
index a73be762..0d3bcd71 100755
--- a/src/application/views/backend/customers.php
+++ b/src/application/views/backend/customers.php
@@ -109,8 +109,10 @@
                     </div>
 
                     <div class="form-group">
-                        <label class="control-label" for="phone-number"><?= lang('phone_number') ?> *</label>
-                        <input id="phone-number" class="form-control required">
+                        <label class="control-label" for="phone-number"><?= lang('phone_number') ?>
+                            <?php echo ('1' === $require_phone_number) ? '*' : ''; ?></label>
+                        <input id="phone-number" class="form-control
+                            <?php echo ('1' === $require_phone_number) ? 'required' : ''; ?>">
                     </div>
 
                     <div class="form-group">
diff --git a/src/application/views/backend/settings.php b/src/application/views/backend/settings.php
index 1c2a1a59..2435f79a 100755
--- a/src/application/views/backend/settings.php
+++ b/src/application/views/backend/settings.php
@@ -177,6 +177,19 @@
                                     <?= lang('require_captcha_hint') ?>
                                 </span>
                             </div>
+                            <div class="form-group">
+                                <label for="require-phone-number">
+                                    <?= lang('require_phone_number') ?>
+                                </label>
+                                <br>
+                                <button type="button" id="require-phone-number" class="btn btn-default" data-toggle="button" aria-pressed="false">
+                                    <span class="glyphicon glyphicon-phone-alt"></span>
+                                    <?= lang('require_phone_number') ?>
+                                </button>
+                                <span class="help-block">
+                                    <?= lang('require_phone_number_hint') ?>
+                                </span>
+                            </div>
                         </div>
                     </div>
                 </fieldset>
diff --git a/src/assets/js/backend_settings.js b/src/assets/js/backend_settings.js
index 6d20efe9..bdb75a86 100644
--- a/src/assets/js/backend_settings.js
+++ b/src/assets/js/backend_settings.js
@@ -71,6 +71,10 @@ window.BackendSettings = window.BackendSettings || {};
                 $('#require-captcha').addClass('active');
             }
 
+            if (setting.name === 'require_phone_number' && setting.value === '1') {
+                $('#require-phone-number').addClass('active');
+            }
+
             if (setting.name === 'display_cookie_notice') {
                 $('#display-cookie-notice').prop('checked', setting.value === '1');
             }
diff --git a/src/assets/js/backend_settings_system.js b/src/assets/js/backend_settings_system.js
index 6a96e881..e2be7a78 100644
--- a/src/assets/js/backend_settings_system.js
+++ b/src/assets/js/backend_settings_system.js
@@ -85,6 +85,12 @@
             value: $('#require-captcha').hasClass('active') === true ? '1' : '0'
         });
 
+        settings.push({
+            name: 'require_phone_number',
+            value: $('#require-phone-number').hasClass('active') === true ? '1' : '0'
+        });
+
+
         // Business Logic Tab
         settings.push({
             name: 'company_working_plan',
diff --git a/src/assets/sql/data.sql b/src/assets/sql/data.sql
index d97512ca..98ae939a 100644
--- a/src/assets/sql/data.sql
+++ b/src/assets/sql/data.sql
@@ -23,6 +23,7 @@ VALUES
     ('terms_and_conditions_content', 'Terms and conditions content.'),
     ('display_privacy_policy', '0'),
     ('privacy_policy_content', 'Privacy policy content.'),
-    ('first_weekday', 'sunday');
+    ('first_weekday', 'sunday'),
+    ('require_phone_number', '1');
 
-INSERT INTO `ea_migrations` VALUES ('13');
+INSERT INTO `ea_migrations` VALUES ('15');