Models
| Model | Voice Format | Latency | Languages |
|---|---|---|---|
| Natural | Telnyx.Natural.<voice> | Low | English |
| NaturalHD | Telnyx.NaturalHD.<voice> | Medium | en, fr, de, es, ar, hi, ja, he, pt |
| KokoroTTS | Telnyx.KokoroTTS.<voice> | Low | — |
| Qwen3TTS | Telnyx.Qwen3TTS.<clone_name> | Medium | en, zh, fr, de, it, ja, ko, pt, ru, es |
| Ultra | Telnyx.Ultra.<voice> | Medium | Multilingual |
Natural & NaturalHD
Pre-built voices. Browse available voices via the Voices API or the Voice Design Lab.Audio Format
Default: MP3. NaturalHD supportsaudio_format query parameter to override:
pcm, wav.
Voice Settings
| Field | Type | Description |
|---|---|---|
voice_speed | float | Playback speed multiplier |
embedding_scale | float | Voice embedding intensity |
diffusion_steps | integer | Quality/latency tradeoff — more steps = higher quality |
phonemizer | string | Phonemizer backend selection |
response_format | string | Output format override |
sampling_rate | integer | Sample rate in Hz |
temperature | float | Synthesis variability |
volume | float | Output volume |
emotion | string | Emotional tone |
Qwen3TTS
Voice cloning model. Thevoice_id is the name of a clone created in the Voice Design Lab. Cloned voice usage may require identity verification.
Requires the clone to belong to your organization.
Audio Format
Always raw PCM — 24kHz, signed 16-bit little-endian, mono. Forced by the backend regardless of anyoutput_format value sent.
Voice Settings
| Field | Type | Default | Description |
|---|---|---|---|
language_boost | string | "Auto" | Target language. Accepted: Auto, English, Chinese, French, German, Italian, Japanese, Korean, Portuguese, Russian, Spanish, or ISO codes |
force_xvector | boolean | false | Force x-vector voice embedding |