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# Chat Started

POST 

Sent when an EVI chat is started.

Reference: https://dev.hume.ai/voice/reference/speech-to-speech-evi/chat-webhooks/chat-started

## Request

### Payload

- `chat_group_id` (string, required) — Unique ID of the **Chat Group** associated with the **Chat** session.
- `chat_id` (string, required) — Unique ID of the **Chat** session.
- `config_id` (string, required, nullable) — Unique ID of the EVI **Config** used for the session.
- `caller_number` (string, required, nullable) — Phone number of the caller in E.164 format (e.g., `+12223333333`). This field is included only if the Chat was created via the [Twilio phone calling](/docs/empathic-voice-interface-evi/phone-calling) integration.
- `chat_start_type` (enum, required) — Indicates whether the chat is the first in a new Chat Group (`new_chat_group`) or the continuation of an existing chat group (`resumed_chat_group`).
  - Allowed values: `new_chat_group`, `resumed_chat_group`
- `custom_session_id` (string, required, nullable) — User-defined session ID. Relevant only when employing a [custom language model](/docs/empathic-voice-interface-evi/custom-language-model) in the EVI Config.
- `start_time` (integer, required) — Unix timestamp (in milliseconds) indicating when the session started.
- `twilio_metadata` (map from string to string, required, nullable) — Twilio metadata associated with the chat. This field is included only if the Chat was created via the [Twilio phone calling](/docs/empathic-voice-interface-evi/phone-calling) integration. Fields may include `call_sid`, `account_sid`, `from_number`, `to_number`, `caller_name`, `caller_number`, `from_city`, `from_state`, `from_zip`, `from_country`, `to_city`, `to_state`, `to_zip`, and `to_country`. If a specific metadata is not available, this field will be set to an empty string.
- `event_name` ("chat_started", optional, default: chat_started) — Always `chat_started`.