Language - Telnyx

BCP-47 language code. Default: en-US.

wss://api.telnyx.com/v2/speech-to-text/transcription?language=es

Auto-Detection

Pass multi to enable automatic language detection. The aliases auto and auto_detect are silently mapped to multi.

?language=multi
?language=auto        # → multi
?language=auto_detect # → multi

Engine Support

Engine	Behavior
Deepgram	BCP-47 codes. `multi` for multi-language mode.
Telnyx	Whisper-based. `auto_detect` disables language hint entirely.
Google	BCP-47 codes.
Azure	BCP-47 codes.
xAI	Language codes such as `en`, `fr`, `de`, and `ja`.
AssemblyAI	Automatic multilingual detection and code switching across supported languages.
Speechmatics	Language codes such as `en`, `es`. Bilingual packs use Telnyx shorthand (e.g. `ar_en`) — mapped internally. Does not support `auto`; defaults to `en` if unrecognized.
Soniox	Automatic language detection. The `language` parameter is ignored — Soniox detects the language from the audio stream.
Parakeet	Automatic multilingual detection. The `language` parameter is ignored — Parakeet always auto-detects.

Supported Languages

For most engines, Telnyx passes the language code directly without validation. The supported set depends on which engine you use. Speechmatics is the exception — Telnyx accepts shorthand codes for bilingual/multilingual packs and maps them to the provider’s language + domain configuration internally.

Engine	Languages	Reference
Deepgram	40+ languages across Deepgram models. Nova-3 supports `multi` (10 languages in code-switching mode). Flux is English-only; Flux-multi supports English, Spanish, French, German, Hindi, Russian, Portuguese, Japanese, Italian, and Dutch, plus `auto`.	Deepgram languages
Telnyx	Whisper-based. 50+ languages. `auto_detect` to skip language hint.	—
Google	125+ languages/locales.	Google Cloud STT languages
Azure	100+ languages/locales.	Azure Speech languages
xAI	25 languages, including Arabic, English, French, German, Hindi, Japanese, Korean, Portuguese, Spanish, and Vietnamese.	xAI Voice API
AssemblyAI	18 languages with native multilingual code switching: English, Spanish, German, French, Portuguese, Italian, Turkish, Dutch, Swedish, Norwegian, Danish, Finnish, Hindi, Vietnamese, Arabic, Hebrew, Japanese, and Mandarin (backed by Universal-3.5 Pro Realtime).	AssemblyAI supported languages
Speechmatics	17+ languages. Standard codes (`en`, `es`, `cy`, `sw`, etc.) plus Telnyx shorthand for bilingual/multilingual packs (`ar_en`, `cmn_en`, `en_ms`, `en_ta`, `cmn_en_ms_ta`). Telnyx maps these internally to Speechmatics `language` + `domain` params — do not pass them raw to the provider.	Speechmatics languages
Soniox	Automatic language detection — no language hint required. The `language` parameter is ignored.	Soniox docs
Parakeet	Automatic multilingual detection — no language hint required. The `language` parameter is ignored.	—

Common Codes

Code	Language
`en` or `en-US`	English (US)
`en-GB`	English (UK)
`es`	Spanish
`fr`	French
`de`	German
`pt-BR`	Portuguese (Brazil)
`it`	Italian
`ja`	Japanese
`zh`	Chinese (Mandarin)
`hi`	Hindi
`ar`	Arabic
`ko`	Korean
`multi`	Multi-language / auto-detect (Deepgram)

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