Django quick and dirty phone validation

phone_validation.py

from django.core.validators import validate_integer
from django.core.exceptions import ValidationError

MIN_PHONE_LENGTH = 11
MAX_PHONE_LENGTH = 15

def validate_phone(input):
    """Validate a phone number"""
    no_symbols = re.sub(r'[^\w]', ' ', input)
    no_symbols_or_whitespace = no_symbols.replace(' ', '')
    validate_integer(no_symbols_or_whitespace)
    length = len(no_symbols_or_whitespace)
    if length < MIN_PHONE_LENGTH or length > MAX_PHONE_LENGTH:
        raise ValidationError('Invalid length of phone')