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

# Language, voice, and speech

> Configure compatible language, speech mode, recognition, and voice settings.

Choose speech mode and language before selecting a voice. These settings determine which voices and speech-recognition fields apply.

## Discover voices

Call `GET /api/v2/agent/voices?targetAccountId=...`. Store the returned voice `id` in `agentVoice`; do not store its display name.

Each catalog entry describes supported languages, compatible speech-to-speech engines, standard text-to-speech support, account availability, and any missing plan requirement.

## Language

`agentLang` accepts the language modes documented by the Agent update schema. Match the selected voice to that language. Use the multilingual mode only when the conversation must move between supported languages.

## Standard speech mode

Set `agentS2SEngine` to `null`. Separate recognition and synthesis settings can then apply:

* `agentSttEngine`
* `agentSttSmartFormatting`
* `agentTtsEngine`
* `agentVoice`

Choose a voice whose catalog entry reports `supportsStandardTts: true` and includes the selected language.

## Speech-to-speech mode

Set `agentS2SEngine` to a supported engine: `openai` or `gemini`. Choose a voice whose `compatibleS2SEngines` includes that engine. Separate STT and TTS settings may not apply in this mode.

Vida manages the supported real-time model behind each engine as capabilities are released. Upcoming OpenAI support includes `gpt-live-1`.

Read staging after the update and verify language, mode, and exact voice ID together. Test a staged call before publishing.