---
title: "Handle Conversation Init"
method: POST
path: "/webhooks/elevenlabs/conversation-init"
tags: ["webhooks", "elevenlabs"]
---

# Handle Conversation Init

`POST /webhooks/elevenlabs/conversation-init`

## Request

- Base URL: `https://api.mentium.io` (the document declares no server; this is the origin it was published from)
- URL: `https://api.mentium.io/webhooks/elevenlabs/conversation-init`
- Auth: none declared

Handle ElevenLabs conversation-init webhook.

## Headers

- `x-webhook-secret` string, nullable

## Request body

- ConversationInitiationRequest: Request payload from ElevenLabs conversation initiation webhook. ElevenLabs calls this webhook when an inbound call is received to get dynamic variables and first_message override for personalization. See: https://elevenlabs.io/docs/agents-platform/customization/personalization/twilio-personalization
  - `caller_id` string, nullable: Caller phone number (E.164)
  - `agent_id` string, nullable: ElevenLabs agent ID
  - `called_number` string, nullable: Called phone number (E.164)
  - `call_sid` string, nullable: Twilio call SID

## Response `200`

Successful Response

- ConversationInitiationResponse: Response to ElevenLabs conversation initiation webhook. Returns dynamic variables and optional conversation overrides to personalize the inbound call experience.
  - `dynamic_variables` object, nullable: Variables available in agent prompt as {{variable_name}}
  - `conversation_config_override` ConversationConfigOverride: Conversation configuration override
    - `agent` AgentOverride: Override for agent configuration
      - `first_message` string, nullable: Override first message the agent says
      - `prompt` object, nullable: Override agent prompt configuration
    - `tts` TtsOverride: Override for TTS (text-to-speech) configuration
      - `voice_id` string, nullable: ElevenLabs voice ID
      - `stability` number, nullable: Voice stability (0-1)
      - `similarity_boost` number, nullable: Voice similarity boost (0-1)
      - `speed` number, nullable: Speech speed multiplier

## Other responses

- `422`: Validation Error

---

[API](https://skmtc.dev/mentium/apis/mentium-api.md) - [All operations](https://skmtc.dev/mentium/apis/mentium-api/llms.txt) - [OpenAPI document](https://skmtc.dev/mentium/apis/mentium-api/revisions/b4ed8e59432e?raw)