Hi, thanks for reaching out.
This is expected with
OpenAI Realtime models.
Realtime is a native speech‑to‑speech pipeline, so it
handles transcription internally and largely bypasses Vapi’s dedicated transcriber. That’s why “transcriber for all” has little effect and why non‑English transcription quality can drop.
Recommendation:
If strong multilingual support is important, avoid Realtime and use Vapi’s standard pipeline with a multilingual transcriber (e.g.
Deepgram Nova (multi),
Google STT Multilingual, or
Gladia). Realtime optimizes for low latency, not multilingual accuracy.
Docs:
[
https://docs.vapi.ai/openai-realtime\
https://docs.vapi.ai/customization/multilingual](
https://docs.vapi.ai/openai-realtimehttps://docs.vapi.ai/customization/multilingual)