In Voximplant scenario, when a call recording ends, I need to take the URL of the recording and send it via a POST request.
I don't understand how can I do this
You can retrieve call record URL by listening to CallEvents.RecordStarted event. The URL then can be passed to your web services using Net.httpRequestAsync function
let call = callPSTN("18881112233", "14434434434");
call.record();
call.addEventListener(CallEvents.RecordStatred, async (e) => {
const recordUrl = e.url;
await Net.httpRequestAsync("https://example.org", {method: "POST", postData: recordUrl});
});