The issue has been resolved and the voice is currently usable. We still recommend setting up fallbacks for any voices for the future to avoid call drops -
https://docs.vapi.ai/voice-fallback-plan

We're noticing issues with calls using the Vapi voice "Emma". If you are using this voice, we recommend switching to another voice while this is resolved, and add voice fallbacks to prevent complete failures - https://docs.vapi.ai/voice-fallback-plan

No other voices are currently impacted. We will update the status page as we know more.