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v52

OpenAPI 3.1.0raw.githubusercontent.com2026-07-311,1941,9384.1 MB
Call Commands

Transcription start

Start real-time transcription. Transcription will stop on call hang-up, or can be initiated via the Transcription stop command.

Expected Webhooks:

  • call.transcription
post/calls/{call_control_id}/actions/transcription_start

Path parameters

call_control_idstring required

Unique identifier and token for controlling the call

Request body

client_statestring

Use this field to add state to every subsequent webhook. It must be a valid Base-64 encoded string.

command_idstring

Use this field to avoid duplicate commands. Telnyx will ignore any command with the same command_id for the same call_control_id.

transcription_engine'Google' | 'Telnyx' | 'Deepgram' | 'Azure' | 'xAI' | 'AssemblyAI' | 'Speechmatics' | 'Soniox' | 'Parakeet' | 'Humain' | 'Reson8' | 'A' | 'B'

Engine to use for speech recognition. Legacy values A - Google, B - Telnyx are supported for backward compatibility.

transcription_tracksstring

Indicates which leg of the call will be transcribed. Use inbound for the leg that requested the transcription, outbound for the other leg, and both for both legs of the call. Will default to inbound.

Example request

{
  "client_state": "aGF2ZSBhIG5pY2UgZGF5ID1d",
  "command_id": "891510ac-f3e4-11e8-af5b-de00688a4901",
  "transcription_engine": "Google",
  "transcription_engine_config": {
    "language": "en",
    "transcription_engine": "Google"
  }
}

Response

Successful response upon making a call control command.

Example response

{
  "data": {
    "result": "ok"
  }
}