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  "path": "/t/gpt-realtime-2-ga-api-what-is-the-correct-audio-format-for-g711-ulaw-twilio-telephony/1380750#post_1",
  "publishedAt": "2026-05-12T18:37:24.000Z",
  "site": "https://community.openai.com",
  "textContent": "Migrating from gpt-realtime-1.5 (beta) to gpt-realtime-2 (GA API) for a Twilio-based voice agent. The GA API rejects the old flat input_audio_format / output_audio_format parameters and requires a nested session.audio.input.format object, but the correct type value for G.711 μ-law (used by Twilio media streams) is unclear.\n\nWhat we’ve tried\n\nBeta API (worked fine):\n{\n“type”: “session.update”,\n“session”: {\n“input_audio_format”: “g711_ulaw”,\n“output_audio_format”: “g711_ulaw”\n}\n}\n\nGA API attempts (all rejected):\n\n  1. “session.input_audio_format” → Unknown parameter: ‘session.input_audio_format’\n  2. format: { type: “g711_ulaw” } → rejected\n\n\n\n{\n“type”: “session.update”,\n“session”: {\n“type”: “realtime”,\n“output_modalities”: [“text”, “audio”],\n“audio”: {\n“input”: {\n“format”: { “type”: “g711_ulaw” }\n},\n“output”: {\n“format”: { “type”: “g711_ulaw” },\n“voice”: “marin”\n}\n}\n}\n}\n\nQuestions\n\n  1. What are the valid values for session.audio.input.format.type in the GA API?\n  2. Is G.711 μ-law (8kHz) supported in gpt-realtime-2 over WebSocket, or only via SIP?\n  3. Is there an official migration guide from the beta to the GA session config schema?\n\n\n\nEnvironment\n\n  * Model: gpt-realtime-2\n  * Connection: WebSocket (wss://api.openai.com/v1/realtime)\n  * Transport: Twilio media streams (G.711 μ-law, 8kHz)\n  * No OpenAI-Beta header (GA API rejects it)\n\n\n\nAny help appreciated — the GA API docs don’t enumerate the valid audio format types for the nested object\nstructure.",
  "title": "Gpt-realtime-2 GA API: What is the correct audio format for g711_ulaw (Twilio/telephony)?"
}