本地号码拨打Twilio号码失败：Content-Type引发502错误

使用本地号码拨打Twilio号码时，Webhook会向/place-call发送POST请求，但最终触发错误回退URL。Twilio提示无法处理目标URL的Content-Type，所有请求必须返回合法的Content-Type，未返回该类型的请求会在Debugger中显示为502 Bad Gateway错误。

Twilio无法处理所提供URL的Content-Type。所有请求都必须返回合法的Content-Type，未返回该类型的请求会在Debugger中显示为502 Bad Gateway错误。

place-call.js 文件 #

const callerNumber = '+1XXXXXXXXXX';
const callerId = 'client:alice';
const defaultIdentity = 'alice';

exports.handler = function (context, event, callback) {
  var url = 'https://' + context.DOMAIN_NAME + '/incoming';

  const client = context.getTwilioClient();

  var to = event.to;
  if (!to) {
    to = event.To;
    if (!to) {
      console.error("Could not find someone to call");
      to = null;
    }
  }
  //  console.log("To: " + JSON.stringify(event));

  if (!to) {
    client.calls.create({
      url: url,
      to: 'client:' + defaultIdentity,
      from: callerId,
    }, function (err, result) {
      // End our function
      if (err) {
        callback(err, null);
      } else {
        callback(null, result);
      }
    });
  } else if (isNumber(to)) {
    console.log("Calling number:" + to);
    client.calls.create({
      url: url,
      to: to,
      from: callerNumber,

    }, function (err, result) {
      // End our function
      if (err) {
        console.log("Error: " + err);
        callback(err, null);
      } else {
        callback(null, result);
      }
    });
  } else {
    client.calls.create({
      url: url,
      to: 'client:' + to,
      from: callerId,
    }, function (err, result) {
      // End our function
      if (err) {
        callback(err, null);
      } else {
        callback(null, result);
      }
    });
  }
};

function isNumber(to) {
  if (to.length == 1) {
    if (!isNaN(to)) {
      console.log("It is a 1 digit long number" + to);
      return true;
    }
  } else if (String(to).charAt(0) == '+') {
    number = to.substring(1);
    if (!isNaN(number)) {
      console.log("It is a number " + to);
      return true;
    };
  } else {
    if (!isNaN(to)) {
      console.log("It is a number " + to);
      return true;
    }
  }
  console.log("not a number");
  return false;
}

incoming.js 文件 #

//'https://' + context.DOMAIN_NAME + '/incoming'

exports.handler = function(context, event, callback) {
  const twiml = new Twilio.twiml.VoiceResponse();
  twiml.say("Congratulations! You have received your first inbound call! Good bye.");

  callback(null, twiml.toString());
};

问题根源在于incoming.js返回TwiML时未指定正确的Content-Type（text/xml），Twilio无法识别返回内容的类型，导致502错误。

修改incoming.js，返回包含响应头的对象，明确指定Content-Type：

exports.handler = function(context, event, callback) {
  const twiml = new Twilio.twiml.VoiceResponse();
  twiml.say("Congratulations! You have received your first inbound call! Good bye.");

  callback(null, {
    headers: {
      'Content-Type': 'text/xml'
    },
    body: twiml.toString()
  });
};

修改后，Twilio就能正确解析返回的TwiML内容，解决502 Bad Gateway错误。

内容的提问来源于stack exchange，提问作者Syed Muzammil Ali