In-Call Transcription

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.
TeXML — XML-based call flow with transcription directives. See the TeXML transcription guide.

Engine selection (Telnyx, Google, Deepgram, Azure, xAI, AssemblyAI, Speechmatics, Soniox) is specified as a parameter on the transcription command. Same engines as WebSocket streaming.

Transcribe speech to text

STT llms.txt

⌘I