Realtime

Accept call

Accept an incoming SIP call and configure the realtime session that will handle it.

post/realtime/calls/{call_id}/accept

Path parameters

call_idstring required

The identifier for the call provided in the realtime.call.incoming webhook.

Request body

type'realtime' required

The type of session to create. Always realtime for the Realtime API.

output_modalitiesstring[]

The set of modalities the model can respond with. It defaults to ["audio"], indicating that the model will respond with audio plus a transcript. ["text"] can be used to make the model respond with text only. It is not possible to request both text and audio at the same time.

instructionsstring

The default system instructions (i.e. system message) prepended to model calls. This field allows the client to guide the model on desired responses. The model can be instructed on response content and format, (e.g. "be extremely succinct", "act friendly", "here are examples of good responses") and on audio behavior (e.g. "talk quickly", "inject emotion into your voice", "laugh frequently"). The instructions are not guaranteed to be followed by the model, but they provide guidance to the model on the desired behavior.

Note that the server sets default instructions which will be used if this field is not set and are visible in the session.created event at the start of the session.

includestring[]

Additional fields to include in server outputs.

item.input_audio_transcription.logprobs: Include logprobs for input audio transcription.

parallel_tool_callsboolean

Whether the model may call multiple tools in parallel. Only supported by reasoning Realtime models such as gpt-realtime-2.

Example request

{
  "audio": {
    "output": {
      "voice": {
        "id": "voice_1234"
      }
    }
  }
}

Response

Call accepted successfully.

Changes

Changed in 4 of the 163 revisions of this API.17

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Sep 16, 20262cd8933757a41See the full diff
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Aug 5, 2026ab0c5306e39012See the full diff
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  added the new gpt-realtime-2.1 enum value to the request property /
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This revision also has 2 changes that name no endpoint, such as unreferenced schemas being removed. See the revision's changelog
May 13, 202674cbcf73838f1See the full diff
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  endpoint added
  endpoint-added
This revision also has 40 changes that name no endpoint, such as unreferenced schemas being removed. See the revision's changelog

Full history