How can I capture a dtmf code on for a call sent out of twilio?

I send calls out by building an html file that contains twiml markup, and use the php lib to place the call to the outgoing number (see e.g.)

$tw_call = $twilio_client->calls->create(
        "+1".$recipient['address'], "+1".$org['twilio_number'], 
        array(
            'Url' => VOICE_CALL_LINK.'/'.$file, (this contains the SAY verbs and text)
            'Timeout' => '30',
            'StatusCallback' => CALLBACK_LINK.'/voice_call_handler.php',
            'StatusCallbackEvent' => array('initiated', 'ringing', 'answered', 'completed')
            )

I want to know if it is possible to record a dtmf code from the call recipient via the method I am using for placing the call?

Can an additional callback url be placed in the text file? If so how would I capture which call the was coming back? Would the call sid be available to the possible callback url within the text file?

Ok I must be missing something. I tried the following:

<Response>
    <Pause length='1'/>
    <Say voice='alice'>$intro</Say>
    <Pause length='1'/>
    <Say voice='alice'>$msg_body</Say>
    <Pause length='1'/>
    <Gather action='absolute html path' numDigits='1'>
        <Say Please respond by selecting 1 for I can come.  Select 2 for I cannot come.</Say>
    </Gather>
</Response>";

I get back from Twilio "an application error has occurred". If I remove the Gather tags and the Say tag within the Gather tags, I receive a perfect call.

Same error occurs if I leave the tags and remove the action and path.

Can you gather responses on outbound calls? I ask because all twilio docs refer to inbound call.

Solution

Twilio developer evangelist here.

In order to capture DTMF tones from a call you can use the <Gather> TwiML verb. This would probably go in the file which contains your <Say> that you point to in the code above. <Say> can be nested within <Gather> in order to allow you to ask the user for input and start taking it as soon as they start typing.

The TwiML might look like this:

<Response>
  <Gather action="/gather_result.php" numDigits="1">
    <Say>Welcome to the free beer hotline, dial 1 for free beer, dial 2 for other beverages.</Say>
  </Gather>
</Response>

Then, when the user dials the number (you can control how many numbers with the numDigits attribute) Twilio will make a request to the URL in the action attribute. Within that request will be a Digits parameter which will contain the numbers the user pressed. The call SID would also be among the parameters.

Let me know if that helps at all.