How to enable gpt-4o-transcribe-diarize for realtime transcription?

Realtime **transcription doc mentions: “**The model to use for transcription. Current options are whisper-1, gpt-4o-mini-transcribe, gpt-4o-mini-transcribe-2025-12-15, gpt-4o-transcribe, and gpt-4o-transcribe-diarize. Use gpt-4o-transcribe-diarize when you need diarization with speaker labels.” But api(/v1/realtime/client_secrets) return: Your organization does not have access to this transcription model. How to enable gpt-4o-transcribe-diarize?