Adding the trigger to Google Spreadsheet

callFLBflow.js

function callFLBflow(name, phoneNumber) {
 var url = 'addYourWebhookUrlHere';
 var data = {
   "name": name,
   "phoneNumber": phoneNumber
 };
 var options = {
   'method' : 'post',
   'contentType': 'application/json',
   // Convert the JavaScript object to a JSON string.
   'payload' : JSON.stringify(data)
 };
 UrlFetchApp.fetch(url, options);
}