Twilio: forward a call to a flow in Twilio - node.js

Question

I want to fordward a call to a Studio Flow after the agent in flex hangs up so a CSAT survey can play for the user.
I created a plugin that calls a function inside Twilio but there is a "Error - 11200" after the forwarding is done.
I replaced the hang up action so it redirects the call to a function in twilio. The function is supossed to send the call to a flow that will play the survey. I suspect the problem has to do with authentication but I can't find much about it.
I'm fairly new to twilio, so any help will be greatly appreciated
This is the part of the plugin that calls the function:
flex.Actions.replaceAction("HangupCall", (payload) => {
console.log('task attributes: ' + JSON.stringify(payload.task.attributes));
if (payload.task.attributes.direction === "inbound") {
// Describe the body of your request
const body = {
callSid: payload.task.attributes.call_sid,
callerId: payload.task.attributes.from,
destination: '+18xxxxxxxx',
Token: manager.store.getState().flex.session.ssoTokenPayload.token
};
// Set up the HTTP options for your request
const options = {
method: 'POST',
body: new URLSearchParams(body),
headers: {
'Content-Type': 'application/x-www-form-urlencoded;charset=UTF-8'
}
};
// Make the network request using the Fetch API
fetch('https://TWILIO INSTANCE.twil.io/TransferUtil', options)
.then(resp => resp.json())
.then(data => console.log(data));
} else {
original(payload);
}
});
And this is the function in twilio:
const TokenValidator = require('twilio-flex-token-validator').functionValidator;
exports.handler = TokenValidator(async function(context, event, callback) {
const response = new Twilio.Response();
response.appendHeader('Access-Control-Allow-Origin', '*');
response.appendHeader('Access-Control-Allow-Methods', 'OPTIONS, POST, GET');
response.appendHeader('Access-Control-Allow-Headers', 'Content-Type');
response.appendHeader('Content-Type', 'application/json');
const client = require('twilio')();
const callSid = event.callSid;
const callerId = event.callerId;
const destination = event.destination;
console.log('Call Sid:', callSid);
console.log('Transfer call from:', callerId, 'to:', destination);
try {
let url = 'https://studio.twilio.com/v2/Flows/FWXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX/Executions';
let call = await client.calls(callSid).update({method: 'POST', url: encodeURI(url)});
console.log(JSON.stringify(call));
response.appendHeader('Content-Type', 'application/json');
response.setBody(call);
callback(null, response);
}
catch (err) {
response.appendHeader('Content-Type', 'plain/text');
response.setBody(err.message);
console.log(err.message);
response.setStatusCode(500);
callback(null, response);
}
});
EDIT:
In the error Log I get this information:

Answer 1

Argh, I read the error wrong. There isn't anything wrong with the Function, the error is coming from the call trying to make a webhook request to the URL https://studio.twilio.com/v2/Flows/FWXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX/Executions. That's the REST API trigger and needs to be requested in the same way as any other API request using your account credentials or API keys.
You should set that URL to the webhook trigger URL, which looks like https://webhooks.twilio.com/v1/Accounts/${ACCOUNT_SID}/Flows/${FLOW_SID}. Then the call will be able to request it as part of a normal webhook flow.