Twilio answering machine detection not leaving message

Question

We are leaving a voice message (using an MP3) using Twilio's answering machine detection. We are seeing in our logs the correct calls to/from the API (answered by answering machine, post of our recorded message)...no error.

But the persons were are testing on, only 1/4 are actually getting a voicemail. The rest receive no voicemail, even though the logs show the correct API calls...? What is happening here?

Here is the code to call the twiml.

 if (Request.Form["AnsweredBy"] != null)
        {
            switch (Request.Form["AnsweredBy"])
            {
                case "machine_end_beep":
                case "machine_end_silence":
                case "machine_end_other":
                    SaveTwilioMessage(transaction.Campaign.Id.ToString());
                    //var machineResponse = new VoiceResponse();
                    if (!string.IsNullOrWhiteSpace(transaction.Campaign.VoicemailMessageUrl))
                    {
                        response.Play(transaction.Campaign.VoicemailMessageUrl);
                    }
                    else
                    {
                        response.Say(transaction.Campaign.VoicemailMessage, voice: _voice);
                    }
                    return new TwiMLResult(response);
                case "human":
                case "fax":
                case "unknown":
                default:
                    break;
            }

And here is the call that generates this:

 var call = await CallResource.CreateAsync(url: callbackUrl, to: new PhoneNumber(phoneNumber), from: new PhoneNumber(fromPhone),machineDetection: "DetectMessageEnd");
        var result = new TelephonicResource(call.Sid);
        return result;

Any thoughts?

Is the message playing out before the machine itself starts to record? — philnash
I think this is possible, but this isn't how Twilio's AMD is supposed to work. I don't think I have the ability to write logic to listen for a stop or a beep. I could record a much longer message, and see if only a part of it gets left maybe? Their service is in beta - so I am expecting some hiccups but not like this. — user3502355

philnash philnash · Accepted Answer · 2017-06-06T15:23:54

Twilio developer evangelist here.

When using Twilio's answering machine detection you have two options for detecting a machine. You set answering machine detection to on by supplying a MachineDetection parameter to the REST API request to make a call.

The MachineDetection parameter can be either Enable or DetectMessageEnd. If you want to leave a message after the answering machine message is complete you need to use DetectMessageEnd.

Then, when you get the webhook callback for the start of the call you get an extra parameter, AnsweredBy, which is either machine_end_beep, machine_end_silence, machine_end_other, human, fax or unknown.

If you get machine_end_beep, machine_end_silence or machine_end_other then you should be able to leave your message then. For other results you can handle them as you would a normal call.

If you just use MachineDetection=Enable then Twilio will attempt to connect you to the call with the result as soon as it has figured out if it is human or machine. If you want to leave a message, I would not choose this option.

Let me know if this helps at all.

Twilio answering machine detection not leaving message

3 Answers