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Telnyx Ultra voices have been upgraded with improved naturalness and stronger multi-lingual support. An auto language boost selector is now available in Mission Control for AI Assistants, and older voices that were not upgraded now carry a DEPRECATED tag.
language_boost parameter without requiring a manual API call.
Voice AI agents live or die on how real they sound. A caller who notices the voice is synthetic loses trust in the conversation, and multi-lingual use cases have historically been where TTS engines break down first, dropping into accent drift or mispronunciation mid-sentence. Upgrading Ultra's core naturalness and multi-lingual handling addresses both failure modes in a single pass. The auto language boost selector removes the most common configuration error, teams no longer need to manually specify a language hint for every assistant. And by clearly marking deprecated voices, Telnyx makes it obvious which voices are current and which to migrate away from, without forcing an immediate switch.
Learn more in the Telnyx Ultra TTS docs or the TTS API docs.