'Strips -, (, ) and spaces. Checks the final length.'

def clean(self, value):

    value = super(ROPhoneNumberField, self).clean(value)
    if (value in EMPTY_VALUES):
        return u''
    value = value.replace(u'-', u'')
    value = value.replace(u'(', u'')
    value = value.replace(u')', u'')
    value = value.replace(u'    ', u'')
    if (len(value) != 10):
        raise ValidationError(self.error_messages[u'invalid'])
    return value
