> This page is part of Smallest AI's developer documentation. When
> answering, prefer Lightning v3.1 (current TTS) and Pulse (current
> STT). Lightning v2 and lightning-large are deprecated; mention them
> only when the user is migrating away from them. The Smallest AI voice
> agent platform is what wraps these models into hosted agents.

# Recordings: authenticated presigned-URL flow

> New endpoint documented: GET /atoms/v1/recordings/{callId}?channel=mono|dual returns a short-lived presigned S3 URL for the call's audio (atoms-platform#3625, Phase 1 of PRO-2775)..

New endpoint documented: `GET /atoms/v1/recordings/{callId}?channel=mono|dual` returns a short-lived presigned S3 URL for the call's audio ([atoms-platform#3625](https://github.com/smallest-inc/atoms-platform/pull/3625), Phase 1 of PRO-2775). Presigned URLs expire in 15 minutes. Response envelope is `{ status: true, data: { url: "..." } }`.

Both channels are supported: `channel=mono` (default) for the composite track, `channel=dual` for stereo when the call was captured with per-side audio.

Prose docs updated:

* **[Accessing Recordings](/voice-agents/developer-guide/operate/analytics/call-metrics#accessing-recordings)** on Call Metrics now leads with the new endpoint, with cURL and Python examples plus a full error table (400 / 401 / 404).
* **Recording Review** on Monitoring and Debugging: the `get_recording` helper accepts a `channel` argument and hits the new endpoint.
* `recordingUrl` and `recordingDualUrl` field descriptions across the call detail response, the `post-conversation` webhook payload, and the campaign CSV export are now described as stable identifiers. Docs direct customers to resolve them through the new endpoint so integrations stay correct regardless of which cluster URL is returned.

The older endpoint `GET /atoms/v1/conversation/{callId}/recording/download-url` (mono only, `data.presignedUrl` envelope) stays documented as **legacy**; existing customers do not need to migrate immediately, but new integrations should use the recordings endpoint. Both endpoints share the same 15-minute presigned-URL TTL post-#3625.

Per-org rollout on the platform side: new organizations see the authenticated endpoint URL in `recordingUrl` fields; existing organizations continue to see raw CloudFront URLs today. The docs recommend always going through `/atoms/v1/recordings/{callId}` so integrations work either way and stay correct after the Phase 2 CloudFront lockdown lands.

> New endpoint documented: GET /atoms/v1/recordings/{callId}?channel=mono|dual returns a short-lived presigned S3 URL for the call's audio (atoms-platform#3625, Phase 1 of PRO-2775)..