# Call center and sales call transcription

> Transcribe every call with the agent and the customer kept apart: send the stereo recording with channel labels and get timed text per side for quality review, coaching and search.

Last updated: 2026-10-08 · HTML: https://console.kolwrite.com/use-cases/call-centers

## A stereo call request

```json
{
  "audio_url": "https://recordings.example.com/2026/10/08/call-5521.wav",
  "model": "oracle",
  "channel_speaker_separation": "overlap",
  "channel_labels": { "0": "Agent", "1": "Customer" },
  "output_format": "json",
  "webhook_url": "https://qa.example.com/hooks/kolwrite"
}
```

Each segment and word carries its channel and label. Use `standard` when people take turns (billed at one model rate) and `overlap` when they talk over each other (billed at the model rate for the greater of the call length or the total detected speech across channels).

## Mono recordings

If both sides are mixed into one channel, use `include_diarization: true` with `num_speakers: 2` instead. Channel separation and diarization cannot be combined in one job.

## At scale

- Start jobs as calls end and receive results by webhook.
- Deduplicate webhook deliveries on `X-KolWrite-Delivery-Id`.
- `base` keeps cost at US$0.48 per call hour for clear lines; `oracle` for noisy or accented calls.
- Recording and transcribing calls requires the consent your jurisdiction demands; that stays your responsibility.

## Questions and answers

### Does channel separation cost extra?

Standard channel separation is included. Overlap mode bills the model rate for the greater of the recording length or the total detected speech.

### Can I label channels with names?

Yes, with `channel_labels`, for example {"0":"Agent","1":"Customer"}.

### How many channels are supported?

Two to eight physical channels.

## Related pages

- [Developers & product teams](https://console.kolwrite.com/use-cases/developers)
- [Legal](https://console.kolwrite.com/use-cases/legal)
- [Enterprises](https://console.kolwrite.com/use-cases/enterprise)
- [Supported languages](https://console.kolwrite.com/languages/)

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