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Documentation Index

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Use a multilingual agent when callers may speak in different languages and you can’t determine which language ahead of time. If you can determine the language at the start of a call (for example, from CRM context or the dialed number), you’ll get better accuracy by keeping the agent single-language and overriding the language per call via the inbound call webhook.

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Granular language selection

In the dashboard, switch the language selector to Multiselect and pick the exact set of languages the agent should support — for example, English (US) + Spanish (ES). What happens at call time:
  • Speech recognition — the agent figures out which of the selected languages the caller is speaking and transcribes accordingly.
  • Voice pronunciation — the agent detects the language of each response and uses the matching pronunciation. If detection fails, it falls back to the first language you selected.
  • Agent text — the agent is allowed to respond in any of the selected languages and chooses based on what the caller speaks (and any instructions you give in the prompt).

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Accuracy trade-offs

Selecting multiple variants of the same base language (for example, en-US and en-GB) does not trigger the multilingual speech-recognition pipeline. The agent stays on the single-language path for that base, with no accuracy penalty.Crossing language families (for example, en-US and es-ES) routes speech recognition to the multilingual pipeline, which is less accurate per language than single-language models. Pick the smallest set of languages you actually need.
From most to least accurate:
  1. Single language — best accuracy. Use this whenever you can.
  2. Multiple variants of the same base language (e.g., en-US + en-GB) — same accuracy as single language for that base.
  3. Multiple languages across families (e.g., en-US + es-ES) — multilingual pipeline; some accuracy loss per language.
  4. Legacy Multilingual setting — broadest coverage, lowest accuracy.

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Legacy Multilingual setting

Older agents may still have the generic Multilingual setting selected. It is preserved so existing agents keep working, but the dashboard now flags it as a legacy setting:
“Multilingual” is a legacy setting. Pick specific languages to update.
The legacy Multilingual setting covers these ten languages: English (US), Spanish (ES), French (FR), German (DE), Hindi (IN), Russian (RU), Portuguese (PT), Japanese (JP), Italian (IT), Dutch (NL). For new agents, pick the specific languages you need instead — narrower sets are more accurate.

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Picks the dashboard won’t allow

Some combinations are blocked at selection time:
  • Voice doesn’t support a language. Each voice (and pinned voice model) only supports a subset of languages. Unsupported combinations are greyed out in the language picker, with a tooltip explaining which voice or voice model is blocking it. Either pick a different voice or remove the unsupported language.
  • No speech-recognition provider covers the combination. Some combinations of languages have no single speech-recognition provider that covers all of them together. The dashboard greys those languages out with the reason — either drop a language or split the use case across multiple agents.