> ## Documentation Index
> Fetch the complete documentation index at: https://developers.telnyx.com/llms.txt
> Use this file to discover all available pages before exploring further.

# In-Call Transcription

> Real-time speech-to-text during live Telnyx voice calls via Voice API or TeXML.

In-call transcription enables real-time STT on live voice calls. The audio codec is managed by the Telnyx platform — no format configuration needed.

Two integration paths:

* **Voice API** — `transcription_start` / `transcription_stop` commands on active calls. See the [Voice API STT guide](/docs/voice/programmable-voice/speech-to-text#voice-api).
* **TeXML** — XML-based call flow with transcription directives. See the [TeXML transcription guide](/docs/voice/programmable-voice/speech-to-text#texml).

Engine selection (Telnyx, Google, Deepgram, Azure, xAI, AssemblyAI, Speechmatics, Soniox) is specified as a parameter on the transcription command. Same engines as [WebSocket streaming](/docs/voice/stt/websocket-streaming/parameters/engines-and-models).