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

# Telnyx

> Use Fish Audio voices for real-time and in-call text-to-speech with Telnyx

[Telnyx](https://telnyx.com) is a carrier-owned global communications platform providing infrastructure for real-time agents — voice AI, SIP trunking, programmable voice, and messaging. Fish Audio is available on Telnyx as a hosted text-to-speech provider: you synthesize Fish Audio voices directly through the Telnyx API and play them in live phone calls via Call Control and TeXML, with no Fish Audio API key required.

## Prerequisites

* A [Telnyx account](https://telnyx.com/sign-up) with an API key
* Python 3.9 or higher with `websockets` 14+ (`pip install websockets`) for the streaming example

## Voices

Telnyx exposes a curated shortlist of voices from the [Fish Audio Voice Library](https://fish.audio/discovery) rather than accepting arbitrary voice IDs. Voices use the format `FishAudio.<Model>.<VoiceId>`, where the model is `s2.1-pro` (latest, default), `s2-pro`, or `s1`:

```text theme={null}
FishAudio.s2.1-pro.933563129e564b19a115bedd57b7406a
```

All curated voices are cross-lingual — any voice can speak any language present in the input text. On S2 models, you can also control delivery with inline emotion tags like `[happy]` or `[whispering]` — see [emotion control](/developer-guide/best-practices/emotion-control) for the full syntax.

See the [Telnyx Fish Audio provider page](https://developers.telnyx.com/docs/voice/tts/providers/fishaudio) for the current voice roster, supported audio formats, and sample rates.

## WebSocket streaming

Stream text in and receive base64-encoded audio chunks in real time:

```python theme={null}
import asyncio
import json
import base64
import websockets

async def tts_stream():
    url = "wss://api.telnyx.com/v2/text-to-speech/speech?voice=FishAudio.s2.1-pro.933563129e564b19a115bedd57b7406a"
    headers = {"Authorization": "Bearer YOUR_TELNYX_API_KEY"}

    async with websockets.connect(url, additional_headers=headers) as ws:
        # 1. Handshake
        await ws.send(json.dumps({
            "text": " ",
            "voice_settings": {"format": "mp3", "sample_rate": 44100}
        }))

        # 2. Send text
        await ws.send(json.dumps({"text": "Hello from Fish Audio on Telnyx."}))

        # 3. Signal end of input
        await ws.send(json.dumps({"text": ""}))

        # 4. Collect audio
        audio_chunks = []
        async for message in ws:
            data = json.loads(message)

            if data.get("error"):
                print(f"Error: {data['error']}")
                break

            if data.get("audio"):
                audio_chunks.append(base64.b64decode(data["audio"]))

            if data.get("isFinal"):
                break

    with open("output.mp3", "wb") as f:
        for chunk in audio_chunks:
            f.write(chunk)

asyncio.run(tts_stream())
```

The handshake requests MP3 output via `voice_settings`; without it, audio is delivered as raw PCM at 24 kHz.

## REST API

Synthesize a complete utterance with a single HTTP request:

```bash theme={null}
curl --request POST \
  --url https://api.telnyx.com/v2/text-to-speech/speech \
  --header 'Authorization: Bearer YOUR_TELNYX_API_KEY' \
  --header 'Content-Type: application/json' \
  --data '{
    "text": "Hello from Fish Audio on Telnyx.",
    "voice": "FishAudio.s2.1-pro.933563129e564b19a115bedd57b7406a",
    "voice_settings": {"format": "mp3", "sample_rate": 44100}
  }' \
  --output output.mp3
```

The response streams back audio bytes. Set `output_type` to `base64_output` or `audio_id` for JSON responses instead.

## Resources

* [Telnyx Fish Audio provider reference](https://developers.telnyx.com/docs/voice/tts/providers/fishaudio)
* [Telnyx WebSocket streaming examples](https://developers.telnyx.com/docs/voice/tts/websocket-streaming/examples)
* [Telnyx REST API examples](https://developers.telnyx.com/docs/voice/tts/rest-api/examples)
* [Fish Audio Voice Library](https://fish.audio/discovery)