diff --git a/apps/establishment/serializers/common.py b/apps/establishment/serializers/common.py
index e4cb389a..9acc2f9e 100644
--- a/apps/establishment/serializers/common.py
+++ b/apps/establishment/serializers/common.py
@@ -1,20 +1,21 @@
 """Establishment serializers."""
 from django.utils.translation import ugettext_lazy as _
+from phonenumber_field.phonenumber import to_python as str_to_phonenumber
 from rest_framework import serializers
 
-from phonenumber_field.modelfields import PhoneNumberField
 from comment import models as comment_models
 from comment.serializers import common as comment_serializers
 from establishment import models
-from location.serializers import AddressBaseSerializer, CitySerializer, AddressDetailSerializer, CityShortSerializer
+from location.serializers import AddressBaseSerializer, CitySerializer, AddressDetailSerializer, \
+    CityShortSerializer
 from main.serializers import AwardSerializer, CurrencySerializer
+from review.serializers import ReviewShortSerializer
 from tag.serializers import TagBaseSerializer
 from timetable.serialziers import ScheduleRUDSerializer
 from utils import exceptions as utils_exceptions
+from utils.serializers import ImageBaseSerializer
 from utils.serializers import (ProjectModelSerializer, TranslatedField,
                                FavoritesCreateSerializer)
-from review.serializers import ReviewShortSerializer
-from utils.serializers import ImageBaseSerializer
 
 
 class ContactPhonesSerializer(serializers.ModelSerializer):
@@ -453,7 +454,23 @@ class CompanyBaseSerializer(serializers.ModelSerializer):
         }
 
     def get_phone_list(self, instance):
+        """Return list of phone numbers."""
         return instance.phones
 
     def get_fax_list(self, instance):
+        """Return list of fax numbers."""
         return instance.faxes
+
+    def validate(self, attrs):
+        """Overridden validate method"""
+        phones = [str_to_phonenumber(phone).as_national for phone in attrs.get('phones')]
+        faxes = [str_to_phonenumber(fax).as_national for fax in attrs.get('faxes')]
+
+        if faxes:
+            if models.Company.objects.filter(faxes__overlap=faxes).exists():
+                raise serializers.ValidationError({'detail': _('Fax is already reserved.')})
+
+        if phones:
+            if models.Company.objects.filter(phones__overlap=phones).exists():
+                raise serializers.ValidationError({'detail': _('Phones is already reserved.')})
+        return attrs