Request for access review — 403 PERMISSION_DENIED on Gemini TTS preview mode

Gemini API
1

Hello Gemini API team,

I’m a Spanish teacher building an educational app in Google AI Studio (an interactive historical-character interview tool for high school students) that relies on Gemini’s voice models so students can practice listening comprehension in Spanish.
Project number: 731706080..

Models requested:

  • gemini-3.1-flash-tts-preview
  • gemini-3.1-flash-live-preview

Observed behavior:

  • Standard text generation models (gemini-2.5-flash, gemini-2.0-flash) work correctly with this same API key/project.
  • Calls to gemini-3.1-flash-tts-preview via generateContent consistently return HTTP 403 PERMISSION_DENIED.
  • The same 403 occurs when connecting to gemini-3.1-flash-live-preview via the Live API.

Could you please review my project and grant access to these preview voice models, or let me know what additional step is needed on my end? This app is intended for classroom use with students, so voice output is an essential accessibility feature, not a nice-to-have.

Thank you very much for your help.

Silvia Moline

2

Hello @Silvia_Moline ,

  • gemini-3.1-flash-tts-preview and gemini-3.1-flash-live-preview are in Public Preview and do not require manual allowlist access.

  • The HTTP 403 PERMISSION_DENIED error occurs because project 731706080... is currently on the unbilled free tier. Linking an active Google Cloud Billing account should remove the error immediately.

  • gemini-2.0-flash was retired on June 1, 2026