country flag and country code not showing in django form and admin

Question

I'm using django-phonenumber_field in my model, but when added a PhoneNumberField in my model, and add it to my forms.py file it does not show a country flag with their country code like this in template, how can i solve this problem?

from phonenumber_field.modelfields import PhoneNumberField
from django.core.validators import RegexValidator

class Product(models.Model):
    user = models.ForeignKey(User,  on_delete=models.CASCADE)
    name = models.CharField(max_length=50)
    category = models.ForeignKey(Category, on_delete=models.CASCADE)
    created_at = models.DateTimeField(auto_now_add=True)
    description = models.TextField(max_length=1000)

    phone_number = PhoneNumberField(validators=[RegexValidator(r'^\d{3}-\d{3}-\d{4}$')])

from phonenumber_field.formfields import PhoneNumberField

class ProductForm(forms.ModelForm):
    phone_number = PhoneNumberField()
    class Meta:
        model = Product
        fields = ['name', 'category', 'description', 'phone_number']

settings.py:

PHONENUMBER_DB_FORMAT = 'INTERNATIONAL'
PHONENUMBER_DB_FORMAT="RFC3966"