Outbound call via SIP trunk

POST https://api.elevenlabs.io/v1/convai/sip-trunk/outbound-call Content-Type: application/json

Handle an outbound call via SIP trunk

Reference: https://elevenlabs.io/docs/api-reference/sip-trunk/outbound-call

• https://api.elevenlabs.io (Production, default)
• https://api.us.elevenlabs.io (Production US)
• https://api.eu.residency.elevenlabs.io (Production EU)
• https://api.in.residency.elevenlabs.io (Production India)
• https://api.sg.residency.elevenlabs.io (Production Singapore)

This endpoint expects a Body_Handle_an_outbound_call_via_SIP_trunk_v1_convai_sip_trunk_outbound_call_post.

• agent_id (string, required)
• agent_phone_number_id (string, required)
• to_number (string, required)
• conversation_initiation_client_data (ConversationInitiationClientDataRequest-Input, optional, nullable)
• telephony_call_config (TelephonyCallConfig-Input, optional)

Successful Response

• success (boolean, required)
• message (string, required)
• conversation_id (string, required, nullable)
• sip_call_id (string, required, nullable)

Validation Error

• detail (list of ValidationError, optional)

• conversation_config_override (ConversationConfigClientOverride-Input, optional)
• custom_llm_extra_body (map from string to any, optional)
• user_id (string, optional, nullable) — ID of the end user participating in this conversation (for agent owner's user identification)
• source_info (ConversationInitiationSourceInfo, optional) — Information about the source of conversation initiation
• branch_id (string, optional, nullable) — ID of the agent branch to use for this conversation
• environment (string, optional, nullable) — Environment to use for resolving environment variables
• starting_workflow_node_id (string, optional, nullable) — If set, start the workflow at this node id instead of the default entry
• procedure_ids (list of string, optional, nullable) — If set, only these procedures are available to the starting agent. Each ID must be attached to that agent; unknown IDs fail conversation start. An empty list disables all of that agent's procedures. Not applied after an agent transfer. Requires enable_procedure_ids_from_client.
• dynamic_variables (map from string to any, optional)

• ringing_timeout_secs (integer, optional, default: 60) — How long to ring the recipient before giving up, in seconds. Note that this will also be limited by the provider's own constraints.
• twilio_call_recording_enabled (boolean, optional, default: false) — Whether to record the call using Twilio call recording. Ignored for non-Twilio providers. Recordings are stored in your Twilio account.
• twilio_machine_detection (TwilioMachineDetectionConfig, optional, nullable) — Configuration for Twilio's carrier-level answering machine detection (AMD). Omit or set to null to disable it. Ignored for non-Twilio providers and for inbound calls. The resulting verdict is delivered as its own answering_machine_detection webhook event, which requires that event to be enabled on the workspace or agent webhook settings; it is not part of the conversation or the post-call webhook. Detection runs asynchronously so it never delays the start of the conversation, and the verdict can arrive at any point during the call -- with detect_message_end, even after it has ended. Twilio bills separately for AMD.

• loc (list of ValidationErrorLocItems, required)
• msg (string, required)
• type (string, required)

• asr (ASRConversationalConfigOverride, optional, nullable) — Configuration for conversational transcription
• turn (TurnConfigOverride, optional, nullable) — Configuration for turn detection
• tts (TTSConversationalConfigOverride, optional, nullable) — Configuration for conversational text to speech
• conversation (ConversationConfigOverride, optional, nullable) — Configuration for conversational events
• agent (AgentConfigOverride-Input, optional, nullable) — Agent specific configuration

Information about the source of conversation initiation

• source (enum, optional, nullable, default: unknown) — Source of the conversation initiation
  • Allowed values: unknown, android_sdk, node_js_sdk, react_native_sdk, react_sdk, js_sdk, python_sdk, widget, sip_trunk, twilio, exotel, genesys, avaya, audiocodes, swift_sdk, whatsapp, twilio_sms, flutter_sdk, zendesk_integration, slack_integration, telegram_integration, intercom_integration, freshdesk_integration, salesforce_integration, template_preview, genesys_bot_connector, subagent_tool
• version (string, optional, nullable) — The SDK version number

How to run Twilio's carrier-level answering machine detection (AMD) on a call.

• mode (enum, optional, default: enable) — How thorough the detection should be. enable returns a verdict as soon as Twilio can tell a human from a machine. detect_message_end also waits for the voicemail greeting to finish, which is what produces the machine_end_* verdicts, but returns a result later.
  • Allowed values: enable, detect_message_end

• keywords (list of string, optional, nullable) — Keywords to boost prediction probability for

• soft_timeout_config (SoftTimeoutConfigOverride, optional, nullable) — Configuration for soft timeout functionality. Provides immediate feedback during longer LLM responses.

• model_id (enum, optional, nullable, default: eleven_flash_v2) — The model to use for TTS
  • Allowed values: eleven_turbo_v2, eleven_turbo_v2_5, eleven_flash_v2, eleven_flash_v2_5, eleven_multilingual_v2, eleven_v3_conversational
• voice_id (string, optional, nullable) — The voice ID to use for TTS
• supported_voices (list of SupportedVoice, optional, nullable) — Additional supported voices for the agent
• stability (double, optional, nullable) — The stability of generated speech
• speed (double, optional, nullable) — The speed of generated speech
• similarity_boost (double, optional, nullable) — The similarity boost for generated speech
• pronunciation_dictionary_locators (list of PydanticPronunciationDictionaryVersionLocator, optional, nullable) — The pronunciation dictionary locators

• text_only (boolean, optional, nullable) — If enabled audio will not be processed and only text will be used, use to avoid audio pricing.
• max_duration_seconds (integer, optional, nullable) — The maximum duration of a conversation in seconds

• first_message (string, optional, nullable) — If non-empty, the first message the agent will say. If empty, the agent waits for the user to start the discussion.
• language (string, optional, nullable) — Language of the agent - used for ASR and TTS
• max_conversation_duration_message (string, optional, nullable) — If non-empty, the message the agent will send when max conversation duration is reached.
• prompt (PromptAgentAPIModelOverride-Input, optional, nullable) — The prompt for the agent

• message (string, optional, nullable) — Message to show when the first soft timeout is reached while waiting for LLM response. Supports dynamic variables (e.g., {{system__time}}, {{custom_variable}}).
• additional_soft_timeout_messages (list of string, optional, nullable) — Extra static filler messages for subsequent soft timeouts in the same LLM generation. The first timeout uses message. If fewer messages are configured than max_soft_timeouts_per_generation, the last configured message is repeated; otherwise a built-in filler is used.

• label (string, required)
• voice_id (string, required)
• description (string, optional, nullable)
• language (string, optional, nullable)
• model_family (enum, optional, nullable)
  • Allowed values: turbo, flash, multilingual, v3_conversational
• optimize_streaming_latency (enum, optional, nullable)
  • Allowed values: 0, 1, 2, 3, 4
• stability (double, optional, nullable)
• speed (double, optional, nullable)
• similarity_boost (double, optional, nullable)

A locator for other documents to be able to reference a specific dictionary and it's version. This is a pydantic version of PronunciationDictionaryVersionLocatorDBModel. Required to ensure compat with the rest of the agent data models.

• pronunciation_dictionary_id (string, required) — The ID of the pronunciation dictionary
• version_id (string, required, nullable) — The ID of the version of the pronunciation dictionary

• prompt (string, optional, nullable) — The prompt for the agent
• llm (enum, optional, nullable) — The LLM to query with the prompt and the chat history. If using data residency, the LLM must be supported in the data residency environment
  • Allowed values: gpt-4o-mini, gpt-4o, gpt-4, gpt-4-turbo, gpt-4.1, gpt-4.1-mini, gpt-4.1-nano, gpt-5, gpt-5.1, gpt-5.2, gpt-5.2-chat-latest, gpt-5.4, gpt-5.4-mini, gpt-5.4-nano, gpt-5.5, gpt-5.6-sol, gpt-5.6-terra, gpt-5.6-luna, gpt-6-astra, gpt-6-sol, gpt-6-luna, gpt-5-mini, gpt-5-nano, gpt-3.5-turbo, gemini-1.5-pro, gemini-1.5-flash, gemini-2.0-flash, gemini-2.0-flash-lite, gemini-2.5-flash-lite, gemini-2.5-flash, gemini-3-pro-preview, gemini-3-flash-preview, gemini-3.1-pro-preview, gemini-3.1-flash-lite-preview, gemini-3.1-flash-lite, gemini-3.5-flash, gemini-3.5-flash-lite, gemini-3.6-flash, gemini-3.7-flash, gemini-3.8-flash, claude-sonnet-4-5, claude-opus-4-7, claude-opus-4-8, claude-opus-5, claude-opus-5-5, claude-sonnet-4-6, claude-sonnet-5, claude-sonnet-4, claude-haiku-4-5, claude-3-7-sonnet, claude-3-5-sonnet, claude-3-5-sonnet-v1, claude-3-haiku, grok-beta, custom-llm, qwen3-4b, qwen3-30b-a3b, qwen36-35b-a3b, qwen35-397b-a17b, gpt-oss-20b, gpt-oss-120b, glm-45-air-fp8, glm-52, deepseek-v41-flash, gemini-2.5-flash-preview-09-2025, gemini-2.5-flash-lite-preview-09-2025, gemini-2.5-flash-preview-05-20, gemini-2.5-flash-preview-04-17, gemini-2.5-flash-lite-preview-06-17, gemini-2.0-flash-lite-001, gemini-2.0-flash-001, gemini-1.5-flash-002, gemini-1.5-flash-001, gemini-1.5-pro-002, gemini-1.5-pro-001, claude-sonnet-4@20250514, claude-sonnet-4-5@20250929, claude-haiku-4-5@20251001, claude-3-7-sonnet@20250219, claude-3-5-sonnet@20240620, claude-3-5-sonnet-v2@20241022, claude-3-haiku@20240307, gpt-5-2025-08-07, gpt-5.1-2025-11-13, gpt-5.2-2025-12-11, gpt-5.4-2026-03-05, gpt-5.4-mini-2026-03-17, gpt-5.4-nano-2026-03-17, gpt-5.5-2026-04-23, gpt-5-mini-2025-08-07, gpt-5-nano-2025-08-07, gpt-4.1-2025-04-14, gpt-4.1-mini-2025-04-14, gpt-4.1-nano-2025-04-14, gpt-4o-mini-2024-07-18, gpt-4o-2024-11-20, gpt-4o-2024-08-06, gpt-4o-2024-05-13, gpt-4-0613, gpt-4-0314, gpt-4-turbo-2024-04-09, gpt-3.5-turbo-0125, gpt-3.5-turbo-1106, watt-tool-8b, watt-tool-70b
• tool_ids (list of string, optional, nullable) — A list of IDs of tools used by the agent
• native_mcp_server_ids (list of string, optional, nullable) — A list of Native MCP server ids to be used by the agent
• knowledge_base (list of KnowledgeBaseLocator, optional, nullable) — A list of knowledge bases to be used by the agent

• type (enum, required) — The type of the knowledge base
  • Allowed values: file, url, text, folder
• name (string, required) — The name of the knowledge base
• id (string, required) — The ID of the knowledge base
• usage_mode (enum, optional, default: auto) — The usage mode of the knowledge base
  • Allowed values: prompt, auto

Request

{
  "agent_id": "string",
  "agent_phone_number_id": "string",
  "to_number": "string"
}

Response

{
  "success": true,
  "message": "string",
  "conversation_id": "string",
  "sip_call_id": "string"
}

SDK Code

import { ElevenLabsClient } from "@elevenlabs/elevenlabs-js";

async function main() {
    const client = new ElevenLabsClient();
    await client.conversationalAi.sipTrunk.outboundCall({
        agentId: "string",
        agentPhoneNumberId: "string",
        toNumber: "string",
    });
}
main();

from elevenlabs import ElevenLabs

client = ElevenLabs()

client.conversational_ai.sip_trunk.outbound_call(
    agent_id="string",
    agent_phone_number_id="string",
    to_number="string",
)

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.elevenlabs.io/v1/convai/sip-trunk/outbound-call"

	payload := strings.NewReader("{\n  \"agent_id\": \"string\",\n  \"agent_phone_number_id\": \"string\",\n  \"to_number\": \"string\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(res)
	fmt.Println(string(body))

}

require 'uri'
require 'net/http'

url = URI("https://api.elevenlabs.io/v1/convai/sip-trunk/outbound-call")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Content-Type"] = 'application/json'
request.body = "{\n  \"agent_id\": \"string\",\n  \"agent_phone_number_id\": \"string\",\n  \"to_number\": \"string\"\n}"

response = http.request(request)
puts response.read_body

import com.mashape.unirest.http.HttpResponse;
import com.mashape.unirest.http.Unirest;

HttpResponse<String> response = Unirest.post("https://api.elevenlabs.io/v1/convai/sip-trunk/outbound-call")
  .header("Content-Type", "application/json")
  .body("{\n  \"agent_id\": \"string\",\n  \"agent_phone_number_id\": \"string\",\n  \"to_number\": \"string\"\n}")
  .asString();

<?php
require_once('vendor/autoload.php');

$client = new \GuzzleHttp\Client();

$response = $client->request('POST', 'https://api.elevenlabs.io/v1/convai/sip-trunk/outbound-call', [
  'body' => '{
  "agent_id": "string",
  "agent_phone_number_id": "string",
  "to_number": "string"
}',
  'headers' => [
    'Content-Type' => 'application/json',
  ],
]);

echo $response->getBody();

using RestSharp;

var client = new RestClient("https://api.elevenlabs.io/v1/convai/sip-trunk/outbound-call");
var request = new RestRequest(Method.POST);
request.AddHeader("Content-Type", "application/json");
request.AddParameter("application/json", "{\n  \"agent_id\": \"string\",\n  \"agent_phone_number_id\": \"string\",\n  \"to_number\": \"string\"\n}", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);

import Foundation

let headers = ["Content-Type": "application/json"]
let parameters = [
  "agent_id": "string",
  "agent_phone_number_id": "string",
  "to_number": "string"
] as [String : Any]

let postData = JSONSerialization.data(withJSONObject: parameters, options: [])

let request = NSMutableURLRequest(url: NSURL(string: "https://api.elevenlabs.io/v1/convai/sip-trunk/outbound-call")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "POST"
request.allHTTPHeaderFields = headers
request.httpBody = postData as Data

let session = URLSession.shared
let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
  if (error != nil) {
    print(error as Any)
  } else {
    let httpResponse = response as? HTTPURLResponse
    print(httpResponse)
  }
})

dataTask.resume()