CODE EXAMPLE FOR JAVASCRIPT

google scripts urlfetchapp hearders and body

var options = {
   "method": "post",
   "headers": {
      "Authorization": "Bearer" + token
   },
   "payload": {
      "From": "+12025551212",
      "To": "+14155551212",
      "Body": "Test from Google Apps Script"
   }
};
var response = UrlFetchApp.fetch(url, options);