---
title: 'Call supervision is live: listen, whisper and barge on live agent calls'
description: >-
  Call supervision is live: team leads listen to live agent calls, whisper
  coaching only the agent hears, or barge in, from a browser, SIP phone or
  mobile.
summary: >-
  Launch: put a supervisor on a live agent call to listen, whisper to the agent
  or barge in, and switch modes through the API. KES 0.50/min from a browser or
  SIP phone.
date: 2026-09-30T00:00:00.000Z
type: blog
---


## Summary

Starting today, a supervisor can join a live call between a customer and one of your agents in one of three modes: **listen** to both sides without being heard, **whisper** to the agent while the customer hears nothing, or **barge** into the conversation. They switch between the three without hanging up, from a browser, a SIP phone or their mobile. It is one API call to start, and a supervisor from a browser or SIP phone costs KES 0.50 a minute.

## Why coaching has to happen during the call

Recordings are good for QA, but they cannot change how a call ends. Coaching that changes the outcome has to happen during the call. That means hearing the call as it happens, a way to speak to the agent without the customer hearing, and the option to take over when the call needs it, all on the same line and without redialling anyone.

## What shipped

- **Three modes on one line.** Listen, whisper and barge, switched through the API at any point. The supervisor's keypad cannot change modes, so nobody barges by accident.
- **Supervisors join from anywhere.** A browser tab running `@sautikit/webrtc`, which answers the supervisor's leg by itself; a desk phone or softphone on a SIP account; or any phone number.
- **Your choice of who knows.** A join tone for the agent, for the agent and the customer, or for nobody. Agents in the browser can also get an on-screen notice, such as "Mary Wanjiku is listening".
- **Events for your dashboards.** Five `call.supervision.*` webhooks, from ringing to ended with the billable seconds.
- **Recording that matches what the customer heard.** Barge audio is in the call recording; listen and whisper are not. The join tone never is.

## A few lines to listen in

```js
import { SautikitClient } from "@sautikit/node";

const sautikit = new SautikitClient({ apiKey: process.env.SAUTIKIT_API_KEY });

await sautikit.calls.supervise(callId, {
  mode: "listen",
  supervisor: { type: "phone", number: "+254700000002" },
  label: "Mary Wanjiku",
});

// Later, once your call.supervision.started webhook arrives:
await sautikit.calls.setSupervisionMode(callId, "whisper");
```

Switching modes waits until the supervisor has answered; before that the API answers `409 calls.supervisor_not_connected`. The [developer guide](/developers/guides/supervise-live-calls) walks through the browser version, the agent's on-screen notice and every event.

## Pricing

A supervisor is billed like any call leg, from answer to leave: **KES 0.50 a minute**, metered per second, from a browser or a SIP phone, or your normal outbound rate when Sautikit rings their mobile. A supervisor who does not answer costs nothing. Every rate is on [/pricing](/pricing).

## FAQ

### What is the difference between call monitoring, whisper and barge?

Monitoring (listen) lets a supervisor hear both sides of a live call without being heard. Whisper lets the supervisor speak to the agent only, so they can coach without the customer hearing. Barge brings the supervisor into the conversation so the agent and the customer both hear them.

### Can more than one supervisor join a call?

One supervisor per call. To hand over, the first supervisor leaves and the next one joins.

### Which calls can be supervised?

A live, answered call between a customer and one of your agents on Sautikit, whether the agent answers in a browser (including Sautikit Desk), on a SIP phone or in a mobile app. Calls answered by an AI agent, conference rooms and callers still waiting in a queue cannot be supervised.

## Get started

- [Call monitoring, whisper and barge](/use-cases/call-monitoring-whisper-barge): how call-centre teams use supervision.
- [Supervise live calls](/developers/guides/supervise-live-calls): the developer guide.