diff --git a/shiftregister/app/dynamic_preferences_registry.py b/shiftregister/app/dynamic_preferences_registry.py
new file mode 100644
index 0000000..af4912e
--- /dev/null
+++ b/shiftregister/app/dynamic_preferences_registry.py
@@ -0,0 +1,17 @@
+from dynamic_preferences.registries import global_preferences_registry
+from dynamic_preferences.types import MultipleChoicePreference
+from dynamic_preferences.types import Section
+import phonenumbers
+
+registration = Section("registation")
+
+
+@global_preferences_registry.register
+class AllowedPhoneCountries(MultipleChoicePreference):
+    section = registration
+    name = "allowed_countries"
+    choices = [
+        (f"{phonenumbers.country_code_for_region(cc)}", cc)
+        for cc in phonenumbers.SUPPORTED_REGIONS
+    ]
+    default = [49, 41, 43]
diff --git a/shiftregister/app/forms.py b/shiftregister/app/forms.py
index be3e18a..ff3e3c4 100644
--- a/shiftregister/app/forms.py
+++ b/shiftregister/app/forms.py
@@ -1,6 +1,11 @@
 from django import forms
 from .models import Helper
 from phonenumber_field.formfields import PhoneNumberField
+from phonenumber_field.validators import validate_international_phonenumber
+from django.core.exceptions import ValidationError
+from dynamic_preferences.registries import global_preferences_registry
+
+global_preferences = global_preferences_registry.manager()
 
 
 def text_input(type=None):
@@ -11,6 +16,17 @@ def text_input(type=None):
     return forms.TextInput(attrs=attrs)
 
 
+def validate_allowed_countries(value):
+    if (
+        not f"{value.country_code}"
+        in global_preferences["registation__allowed_countries"]
+    ):
+        raise ValidationError(
+            "Vorwahl nicht Erlaubt, bitte wende dich an den Infodesk oder schicke uns eine Mail"
+        )
+    return value
+
+
 class RegisterForm(forms.Form):
     name = forms.CharField(
         max_length=Helper.name.field.max_length, label="Name", widget=text_input()
@@ -21,6 +37,10 @@ class RegisterForm(forms.Form):
         label="Handynummer für Benachrichtigungen",
         help_text="Wir nutzen deine Handynummer, um dir Benachrichtigungen zu deinen Schichten zu schicken. Wir löschen alle Daten 7 Tage nach dem Festival.",
         widget=text_input("tel"),
+        validators=[
+            validate_international_phonenumber,
+            validate_allowed_countries,
+        ],
     )
     okf = forms.BooleanField(label="Ich bin damit einverstanden, SMS zu erhalten.")