Twilio Programmable Fax TwiML bin receive handler error 11200 - twilio

Question

I've set up a TwiML bin for handling incoming faxes on one of my numbers. The bin looks like (if I remember correctly, there is no dashboard for editing existing fax TwiML bins yet :) )
<?xml version="1.0" encoding="UTF-8"?>
<Response>
<Receive action="my/api/endpoint" methods="POST" storeMedia="false"/>
</Response>
I don't believe it is an issue with my TwiML bin, however. Going into the debugger, I see 11200 errors, connection issues with the service. It seems the connection issue is with the TwiML bin handler:
POST https://handler.twilio.com/fax/received
Request message text: "; will retry until 2018-04-20T23:07:25.893Z"
Response body: "HTTP Retrieval Failure"
The issue is on Twilio's side, right?
Anything else I should check?

Answer 1

I had same error.
The error is just because twilio did not get the expected result back from your action endpoint.
First you should return the following XML with action attribute that you are doing correctly
<?xml version="1.0"?>
<Response>
<Receive action="/api/fax/received/file"/>
</Response>
And second you should return 200 OK response on /api/fax/received/file. Meaning you should respond with valid response confirming that you got that fax file to twilio i.e 200 response code.
In your case:
Now you should have <your-domain>/my/api/endpoint active and reachable from twilio as you have action="my/api/endpoint". and when twilio calls this endpoint, you should return 200 OK response confirming that you got the file otherwise twilio will think that there is error "HTTP Retrieval Failure".
check your action="my/api/endpoint"(/fax/received) and make sure you respond back with 200.
If programming language does not matter to you then my code for both endpoint looks like as follows in PHP. First method (Endpoint) is mapped with the phone-number on twilio and second is for action attribute. This is how I got rid of that error.
// this is /api/incoming/fax endpoint and I on twilio i have put this URL on the phone number
// this method will be called via /api/incoming/fax when any incoming fax
public function incomingFax(Request $request){
$twimlResponse = new \SimpleXMLElement("<Response></Response>");
$recieveEl = $twimlResponse->addChild('Receive');
$recieveEl->addAttribute('action', '/api/fax/received/file');
return response($twimlResponse->asXML(), 200)
->header('Content-Type', 'text/xml');
}
// this is /api/fax/received/file endpoint which will be called by twilio
//always return 200
public function receivedFaxFile(Request $request)
{
$inputs = $request->all();
$from = $inputs['From'];
$media_url = $inputs['MediaUrl'];
if(isset($inputs['MediaUrl'])&&isset($inputs['To'])){
$thread = Thread::where(array("out_did"=>$to))->latest()->first();
$slack = new Slack(config("app.slack_access_key"));
$this->sendAttachment($from,$to,$media_url,$thread->thread_ts);
}
return response('', 200); // should return 200
}