def unknown_service(request, username=None, id_string=None):
    r = HttpResponse(u"Unknown SMS Gateway Service", content_type='text/plain')
    r.status_code = 400
    return r
400 view for request with unknown service name
dataset/ETHPy150Open kobotoolbox/kobocat/onadata/apps/sms_support/providers/__init__.py/unknown_service