Live Transcripts

Subscribe to live call events (SSE)

Changed on

Real-time streaming of user speech (STT) and agent speech (TTS) events for an active call via Server-Sent Events.

The connection is real-time — events stream directly from the call runtime as they are produced. The SSE connection auto-closes when the call ends (sse_close event). Only active calls can be subscribed to; completed calls return a 400 error.

Transcript event types:

  • user_interim_transcription — Partial, in-progress transcription as the user speaks. Use for live preview only; will be superseded by user_transcription.
  • user_transcription — Final transcription for a completed user speech turn.
  • tts_completed — Fired when the agent finishes speaking a TTS segment. Includes the spoken text and optionally TTS latency.

Lifecycle events:

  • sse_init — Sent immediately when the SSE connection is established.
  • sse_close — Sent when the call ends, right before the server closes the connection.

Other event types (e.g. tool_call_start, pre_call_api, agent_log, metrics) are also sent on this stream.

  • call_start
  • call_end
  • turn_latency
  • metrics
  • agent_node_state
  • hopping
  • knowledgebase
  • variable_extraction
  • pre_call_api
  • post_call_api
  • agent_error
  • agent_log
  • tool_call_start
  • tool_call_end
  • tool_call_error
  • call_cancelled
  • call_recording
get/events

Request

  • Base URL
    https://api.smallest.ai/atoms/v1
  • URL
    https://api.smallest.ai/atoms/v1/events
  • Auth
    HTTP bearer

Query parameters

callIdstring required
Example:CALL-1758124225863-80752e

The call ID to subscribe events for. Missing or invalid values return 400.

Headers

X-Organization-Idstring

Required when using session-cookie auth. API-token auth may infer the organization from the token.

Response

SSE event stream established successfully

Changes

  • 7aec6f3099deRevision changes
    • breaking

      the response's property type changed from object to array for status

  • ff0bafe7239aRevision changes
    • warning

      added the new agent_error enum value to the response property for the response status

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      added the new agent_log enum value to the response property for the response status

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      added the new agent_node_state enum value to the response property for the response status

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      added the new call_cancelled enum value to the response property for the response status

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      added the new call_end enum value to the response property for the response status

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      added the new call_recording enum value to the response property for the response status

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      added the new call_start enum value to the response property for the response status

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      added the new metrics enum value to the response property for the response status

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      added the new post_call_api enum value to the response property for the response status

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