--- title: "Accept call" method: POST path: "/live/sessions/{session_id}/accept" tags: ["Live"] --- # Accept call `POST /live/sessions/{session_id}/accept` Accept an incoming SIP call. Supply session with type live, the model, and startup configuration. Before accepting calls, follow the [Live prompting guide](https://developers.openai.com/api/docs/guides/live-prompting) to write frontend conversation instructions and a separate backend prompt. SIP media format is negotiated; omit audio.format. ## Path parameters - `session_id` string, required ## Request body - LiveCallAcceptRequest — Accept an incoming SIP call with Live startup configuration. - `session` LiveCallAcceptSession, required — Startup configuration for accepting an incoming Live SIP call. Follow the [Live prompting guide](https://developers.openai.com/api/docs/guides/live-prompting) when writing frontend and backend instructions. - `model` union, required — The Live model. Required in the session configuration for every transport; do not pass it as a URL query parameter. - string - 'gpt-live-1' - `instructions` string, nullable — Frontend instructions for voice, conversation, interruptions, and when to delegate. Start with the [Live prompting guide](https://developers.openai.com/api/docs/guides/live-prompting); put business rules and tool workflows in a separate [backend prompt](https://developers.openai.com/api/docs/guides/live-delegation#start-with-your-existing-backend-prompt). Limited to 16,384 client-supplied tokens. Omitted or blank instructions use server defaults. Immutable after startup. - `audio` LiveMediaSessionAudioParam — Startup audio output configuration. WebRTC and SIP negotiate the media format; audio.format is only accepted for primary WebSockets. Voice cannot change after startup. - `output` LiveInitialSessionAudioOutputParam — Settings for speech generated by the Live model. Choose the voice before starting the session. - `voice` union — The voice used for Live speech, as a built-in voice name or a custom voice object containing its ID. Defaults to `marin` and cannot change after startup. - union - string - 'alloy' | 'ash' | 'ballad' | 'beacon' | 'bossa' | 'cedar' | 'cinder' | 'coral' | 'delta' | 'echo' | 'gleam' | 'marin' | 'meridian' | 'quartz' | 'ripple' | 'sage' | 'shimmer' | 'stone' | 'tempo' | 'verse' | 'vesper' | 'willow' - LiveCustomVoiceParam - `id` string, required - `delegation` union - LiveClientDelegationParam — Delegate tasks to your application. The Live session emits delegation events that your backend handles. - `type` 'client', required — The delegation owner. Always `client` for tasks handled by your application. - LiveResponsesDelegationParam — Delegate tasks to a Responses model managed by the Live session. - `type` 'responses', required — The delegation owner. Always `responses` for tasks handled by the Responses API. - `responses` LiveResponsesDelegationSettingsInputParam, required — Model, prompt, and tool settings for tasks delegated by the Live session to a Responses backend. - `model` string, required — The model used for server-owned Responses delegations. - `instructions` string, nullable — Instructions for the delegated Responses model, separate from Live instructions. See [backend prompting](https://developers.openai.com/api/docs/guides/live-delegation#start-with-your-existing-backend-prompt). - `max_output_tokens` integer, nullable — Maximum number of output tokens for each delegated response. - `service_tier` 'auto' | 'default' | 'fast_tier_temp_pilot' | 'flex' | 'priority' | 'ultrafast' - `reasoning` LiveDelegationReasoningInputParam — Reasoning options for Responses requests made on behalf of the Live session. - `effort` 'none' | 'minimal' | 'low' | 'medium' | 'high' | 'xhigh' - `summary` 'concise' | 'detailed' | 'auto' - `text` LiveDelegationTextInputParam — Text generation options for the Live session’s Responses backend. - `verbosity` 'low' | 'medium' | 'high' - `tools` union[] — Tools available to the Responses backend while it handles tasks delegated by the Live model. - union - … - `tool_choice` union — Controls which tool the Responses backend uses when handling a task delegated by the Live model. - 'auto' | 'none' | 'required' - LiveFunctionToolChoiceParam - … - LiveMCPToolChoiceParam - … - `parallel_tool_calls` boolean, nullable — Whether the delegated Responses model may request multiple tool calls in a single response. - `store` boolean — Whether to store the session for later forking and recording download. Defaults to false for new sessions. - `input` LiveInitialItem[] — Ordered text-only history supplied before startup. Supports developer, user, and assistant messages with one text part each; at most 128 messages and 8,192 rendered tokens in total. - union — A developer, user, or assistant message supplied as text history before the Live session starts. - LiveInitialDeveloperMessageItemParam — A developer message included in the initial text history of a Live session. - `id` string, nullable — An optional identifier for the supplied history message. Live uses the message’s role and text to initialize the conversation. - `type` 'message' — The history item type. Always `message`. - `status` 'incomplete' | 'completed' - `role` 'developer', required — The author of this history message. Always `developer`. - `content` LiveInitialInputTextContentPartParam[], required — The message content. Supply exactly one text part for the initial Live conversation history. - `type` 'input_text' — The text content type. Always `input_text`. - `text` string, required — The message text to include in the Live session’s initial conversation history. - LiveInitialUserMessageItemParam — A user message included in the initial text history of a Live session. - `id` string, nullable — An optional identifier for the supplied history message. Live uses the message’s role and text to initialize the conversation. - `type` 'message' — The history item type. Always `message`. - `status` 'incomplete' | 'completed' - `role` 'user', required — The author of this history message. Always `user`. - `content` LiveInitialInputTextContentPartParam[], required — The message content. Supply exactly one text part for the initial Live conversation history. - `type` 'input_text' — The text content type. Always `input_text`. - `text` string, required — The message text to include in the Live session’s initial conversation history. - LiveInitialAssistantMessageItemParam — An assistant message included in the initial text history of a Live session. - `id` string, nullable — An optional identifier for the supplied history message. Live uses the message’s role and text to initialize the conversation. - `type` 'message' — The history item type. Always `message`. - `status` 'incomplete' | 'completed' - `role` 'assistant', required — The author of this history message. Always `assistant`. - `content` union[], required — The message content. Supply exactly one text part for the initial Live conversation history. - union - … - `type` 'live', required — The session type. Always `live`. ## Response `200` Session accept request accepted. ## Changes - **2026-09-10** `d3c0cb1ebbed` — 1 info - endpoint added [Change history](https://skmtc.dev/openai/apis/openapi/changes/live/sessions/:session_id/accept/post.md) --- [API](https://skmtc.dev/openai/apis/openapi.md) · [All operations](https://skmtc.dev/openai/apis/openapi/llms.txt) · [OpenAPI document](https://skmtc.dev/openai/apis/openapi/revisions/9c523485a79e?raw)