Telnyx STT

Telnyx provides streaming speech-to-text over WebSocket. The plugin resamples audio to your configured rate, sends it as raw linear16 frames, and emits transcripts as they arrive.

Vision Agents uses Stream Video for real-time WebRTC transport by default. External WebRTC transports are supported as well. Most AI providers offer free tiers to get started.

Get your Telnyx API key from the Telnyx Mission Control Portal.

Telnyx also provides text-to-speech, an LLM, and PSTN telephony. You can use all four in the same agent.

Telnyx STT does not emit VAD signals, so pair it with a turn detector such as Smart Turn.

Installation

uv add "vision-agents[telnyx]"

Quick start

from vision_agents.core import Agent, User
from vision_agents.plugins import getstream, smart_turn, telnyx

agent = Agent(
    edge=getstream.Edge(),
    agent_user=User(name="Assistant", id="agent"),
    instructions="You are a helpful voice assistant.",
    stt=telnyx.STT(),
    llm=telnyx.LLM(),
    tts=telnyx.TTS(),
    turn_detection=smart_turn.TurnDetection(),
)

Set TELNYX_API_KEY in your environment or pass api_key directly.

Parameters

stt = telnyx.STT(
    transcription_engine="Telnyx",
    language="en",
    sample_rate=16000,
    interim_results=False,
)

Name	Type	Default	Description
`transcription_engine`	`str`	`"Telnyx"`	Engine to transcribe with (e.g. `Telnyx`, `Deepgram`, `Speechmatics`, `Soniox`)
`language`	`str`	`"en"`	Language code
`sample_rate`	`int`	`16000`	Rate in Hz audio is resampled to (use `8000` for telephony audio)
`interim_results`	`bool`	`False`	Emit partial transcripts (honoured per engine)
`model`	`str`	`""`	Optional engine-specific model id
`api_key`	`str`	`None`	API key (defaults to `TELNYX_API_KEY` env var)

Set sample_rate=8000 when transcribing telephony audio from the Telnyx or Twilio plugins to avoid upsampling PCMU frames.

Engines and interim results

Measured against the live API with the same audio, Speechmatics and Soniox stream partial transcripts, while Telnyx and Deepgram accept the parameter and return finals only.

stt = telnyx.STT(transcription_engine="Speechmatics", interim_results=True)

The engine catalogue is served by Telnyx and is not validated locally.

Next steps

Telnyx TTS

Streaming text-to-speech

Telnyx LLM

OpenAI-compatible chat completions

Telnyx Telephony

PSTN calls via Call Control

Turn Detection

Pair with a turn detector

Overview

Language Models

Realtime

Speech-to-Text

Text-to-Speech

Vision & Video

Avatars

Turn Detection

Infrastructure

Edge Transport

Telephony

Custom Integrations

Installation

Quick start

Parameters

Engines and interim results

Next steps

Telnyx TTS

Telnyx LLM

Telnyx Telephony

Turn Detection

​Installation

​Quick start

​Parameters

​Engines and interim results

​Next steps

Telnyx TTS

Telnyx LLM

Telnyx Telephony

Turn Detection

Installation

Quick start

Parameters

Engines and interim results

Next steps