Create session

POST/live/sessions

Create a Live WebRTC session. Start with the Live prompting guide.

Body ParametersJSONExpand Collapse

session: MediaSessionConfig { model, audio, client, 4 more }

Startup configuration for the Live session.

model: string or "gpt-live-1"

The Live model. Required in the session configuration for every transport; do not pass it as a URL query parameter.

One of the following:

string

"gpt-live-1"

The Live model. Required in the session configuration for every transport; do not pass it as a URL query parameter.

audio: optional object { output }

Startup audio configuration. WebRTC and SIP negotiate their audio format on the media transport.

output: optional object { voice }

Settings for speech generated by the Live model. Choose the voice before starting the session.

voice: optional string or "alloy" or "ash" or "ballad" or 19 more or CustomVoice { id }

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.

One of the following:

string

"alloy" or "ash" or "ballad" or 19 more

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.

One of the following:

"alloy"

"ash"

"ballad"

"beacon"

"bossa"

"cedar"

"cinder"

"coral"

"delta"

"echo"

"gleam"

"marin"

"meridian"

"quartz"

"ripple"

"sage"

"shimmer"

"stone"

"tempo"

"verse"

"vesper"

"willow"

CustomVoice object { id }

id: string

minLength1

maxLength128

client: optional ClientConfig { data_channel }

Startup-only capabilities for an untrusted frontend attached to a unified WebRTC session. Trusted sideband connections are unaffected.

data_channel: DataChannelConfig { allowed_client_events, allowed_server_events }

Client and server event permissions for the WebRTC frontend data channel.

allowed_client_events: optional "all" or array of string

Client event types that the frontend data channel may send. Use ‘all’ to allow every client event; an empty array allows none. Omission preserves the existing allow-all behavior.

One of the following:

"all"

array of string

allowed_server_events: optional "all" or array of ServerEventSelector { type, response_event }

Server events that may be sent to the frontend data channel. Use ‘all’ to allow every server event; an empty array allows none. Omission preserves the existing allow-all behavior. Responses events use an object with type ‘response.event’ and a response_event selector.

One of the following:

"all"

array of ServerEventSelector { type, response_event }

type: string

The outer Live server event type. Use ‘response.event’ for Responses events.

minLength1

maxLength256

response_event: optional string

The nested Responses event type. Required when type is ‘response.event’; forbidden for other event types.

minLength1

maxLength256

delegation: optional ClientDelegation { type } or object { responses, type } or null

Who handles tasks delegated by the Live model. Omitted or null selects your application; use responses to let the API manage a Responses backend.

One of the following:

ClientDelegation object { type }

Delegate tasks to your application. The Live session emits delegation events that your backend handles.

type: "client"

The delegation owner. Always client for tasks handled by your application.

Responses object { responses, type }

Delegate tasks to a Responses model managed by the Live session.

responses: ResponsesDelegationConfig { model, instructions, max_output_tokens, 6 more }

Backend model, prompt, and tools used when the Live session delegates a task to Responses.

model: string

The model used for server-owned Responses delegations.

instructions: optional string or null

Instructions for the delegated Responses model, separate from Live instructions. See backend prompting.

max_output_tokens: optional number or null

Maximum number of output tokens for each delegated response.

minimum16

parallel_tool_calls: optional boolean or null

Whether the delegated Responses model may request multiple tool calls in a single response.

reasoning: optional object { effort, summary } or null

Reasoning settings passed to each delegated Responses request.

effort: optional "none" or "minimal" or "low" or 3 more or null

How much reasoning effort the delegated Responses model should use. Supported values depend on the backend model.

One of the following:

"none"

"minimal"

"low"

"medium"

"high"

"xhigh"

summary: optional "concise" or "detailed" or "auto" or null

The reasoning summary to request from the delegated Responses model, when supported.

One of the following:

"concise"

"detailed"

"auto"

service_tier: optional "auto" or "default" or "fast_tier_temp_pilot" or 3 more or null

Service tier for delegated Responses requests.

One of the following:

"auto"

"default"

"fast_tier_temp_pilot"

"flex"

"priority"

"ultrafast"

text: optional object { verbosity } or null

Text generation settings passed to each delegated Responses request.

verbosity: optional "low" or "medium" or "high" or null

The amount of detail in text generated by the Responses backend. This does not configure the Live model’s spoken delivery.

One of the following:

"low"

"medium"

"high"

tool_choice: optional "auto" or "none" or "required" or object { name, type } or object { name, server_label, type }

Controls which tool the Responses backend uses when handling a task delegated by the Live model.

One of the following:

LiveToolChoiceEnum = "auto" or "none" or "required"

One of the following:

"auto"

"none"

"required"

LiveFunctionToolChoiceParam object { name, type }

minLength1

maxLength64

type: "function"

LiveMCPToolChoiceParam object { name, server_label, type }

minLength1

maxLength64

server_label: string

minLength1

maxLength64

type: "mcp"

tools: optional array of FunctionTool { name, type, description, 2 more } or object { type }

Tools available to the Responses backend while it handles tasks delegated by the Live model.

One of the following:

FunctionTool object { name, type, description, 2 more }

A function tool available to the Responses backend when the Live model delegates a task.

The name the delegated Responses model uses when calling this function.

type: "function"

The tool type. Always function.

description: optional string or null

What the function does and when the delegated Responses model should call it.

parameters: optional map[unknown] or null

A JSON Schema object describing the arguments accepted by the function.

strict: optional boolean or null

Whether the delegated Responses model must follow the function’s parameter schema exactly.

WebSearch object { type }

A web search tool available to the Live session’s Responses backend.

type: "web_search"

The tool type. Always web_search.

type: "responses"

The delegation owner. Always responses for tasks handled by the Responses API.

input: optional array of InitialItem

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.

One of the following:

Developer object { content, role, id, 2 more }

A developer message included in the initial text history of a Live session.

content: array of object { text, type }

The message content. Supply exactly one text part for the initial Live conversation history.

text: string

The message text to include in the Live session’s initial conversation history.

type: optional "input_text"

The text content type. Always input_text.

role: "developer"

The author of this history message. Always developer.

id: optional string or null

An optional identifier for the supplied history message. Live uses the message’s role and text to initialize the conversation.

status: optional "incomplete" or "completed" or null

The supplied message’s status. Live uses its text as history and does not resume an incomplete message.

One of the following:

"incomplete"

"completed"

type: optional "message"

The history item type. Always message.

User object { content, role, id, 2 more }

A user message included in the initial text history of a Live session.

content: array of object { text, type }

The message content. Supply exactly one text part for the initial Live conversation history.

text: string

The message text to include in the Live session’s initial conversation history.

type: optional "input_text"

The text content type. Always input_text.

role: "user"

The author of this history message. Always user.

id: optional string or null

An optional identifier for the supplied history message. Live uses the message’s role and text to initialize the conversation.

status: optional "incomplete" or "completed" or null

The supplied message’s status. Live uses its text as history and does not resume an incomplete message.

One of the following:

"incomplete"

"completed"

type: optional "message"

The history item type. Always message.

Assistant object { content, role, id, 2 more }

An assistant message included in the initial text history of a Live session.

content: array of object { text, type } or object { text, type }

The message content. Supply exactly one text part for the initial Live conversation history.

One of the following:

Text object { text, type }

Assistant text supplied as conversation history when starting a Live session.

text: string

The message text to include in the Live session’s initial conversation history.

type: optional "text"

The text content type. Always text.

OutputText object { text, type }

Assistant output text supplied as conversation history when starting a Live session.

text: string

The message text to include in the Live session’s initial conversation history.

type: "output_text"

The text content type. Always output_text.

role: "assistant"

The author of this history message. Always assistant.

id: optional string or null

An optional identifier for the supplied history message. Live uses the message’s role and text to initialize the conversation.

status: optional "incomplete" or "completed" or null

The supplied message’s status. Live uses its text as history and does not resume an incomplete message.

One of the following:

"incomplete"

"completed"

type: optional "message"

The history item type. Always message.

instructions: optional string or null

Frontend instructions for voice, conversation, interruptions, and when to delegate. Start with the Live prompting guide; put business rules and tool workflows in a separate backend prompt. Limited to 16,384 client-supplied tokens. Omitted or blank instructions use server defaults. Immutable after startup.

store: optional boolean

Whether to store the session for later forking and recording download. Defaults to false for new sessions.

transport: object { sdp, type }

WebRTC transport with the browser’s SDP offer.

sdp: string

Session Description Protocol message for the WebRTC connection.

minLength1

type: "webrtc"

The transport used for the Live session. Always webrtc.

ReturnsExpand Collapse

session: object { id }

The newly created Live session. Use its ID for session controls and sideband connections.

id: string

Opaque session identifier. Preserve the returned value unchanged, including its prefix.

transport: object { sdp, type }

WebRTC transport with the SDP answer.

sdp: string

Session Description Protocol message for the WebRTC connection.

minLength1

type: "webrtc"

The transport used for the Live session. Always webrtc.

Create session

curl https://api.openai.com/v1/live/sessions \
  -H "Authorization: Bearer $OPENAI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"session":{"model":"gpt-live-1","instructions":"Be concise. Ask for clarification when needed."},"transport":{"type":"webrtc","sdp":"<SDP offer>"}}'

{
  "session": {
    "id": "live_123"
  },
  "transport": {
    "type": "webrtc",
    "sdp": "<SDP answer>"
  }
}

Returns Examples

{
  "session": {
    "id": "live_123"
  },
  "transport": {
    "type": "webrtc",
    "sdp": "<SDP answer>"
  }
}

Suggested

Suggested

Create session

Body ParametersJSONExpand Collapse

ReturnsExpand Collapse

Create session

Returns Examples