Text-to-Speech WebSocket errors

HTTP Errors (Handshake)

These occur during the WebSocket upgrade request, before the connection is established.

Code	Cause
400	Invalid parameters — unsupported provider, missing required fields, or invalid voice format
401	Missing or invalid API key
403	Ultra model restricted on public WebSocket endpoint. Use REST API for Ultra.
403	Cloned voice restricted — organization requires identity verification for cloned voices (Qwen3TTS, Bayan, Minimax, Resemble clones)

After the connection is established, errors arrive as JSON frames:

{
  "error": "Error in audio response"
}

The connection closes shortly after an error frame.

Error	Cause
`"Error in audio response"`	The TTS provider returned an error during synthesis
`"Error in remaining audio response"`	Provider error while synthesizing buffered text during connection close

Symptom	Cause	Fix
Connection rejected (400)	Invalid voice format	Use `Provider.Model.VoiceId` format (e.g., `Telnyx.KokoroTTS.af_heart`)
Connection rejected (401)	Missing auth	Pass `Authorization: Bearer <key>` header during WebSocket upgrade
No audio after connecting	Missing handshake	Send `{"text": " "}` as first frame
`audio` field is `null`	Expected behavior	For streamed providers (Telnyx, Minimax, Resemble, Inworld), audio arrives in separate streamed frames
Text sent but no response	Sentence buffering	Text is buffered until a sentence boundary. Send more text, use `flush: true`, or end with punctuation
Ultra not working on WebSocket	Intentional restriction	Ultra is REST-only. Use `POST /v2/text-to-speech/speech`
Cloned voice rejected	Identity verification required	Complete L2 verification in the Telnyx Portal