---
title: "Start an outbound chat conversation"
method: POST
path: "/chat/outbound"
tags: ["chat"]
---

# Start an outbound chat conversation

`POST /chat/outbound`

Create a new outbound WhatsApp or SMS conversation for a chat agent.

## Headers

- `Authorization` string, required

## Request body

- OutboundChatRequest — Request to start an outbound SMS or WhatsApp chat conversation.
  - `agent_id` string, uuid, required — The ID of the chat agent that will handle the conversation.
  - `channel` 'sms' | 'whatsapp', required — Outbound messaging channel.
  - `to_number` string, required — Recipient phone number in E.164 format.
  - `from_number` string, required — Twilio sender phone number in E.164 format.
  - `initial_message` string — Freeform opening message. For WhatsApp, this is only valid within the 24-hour customer service window.
  - `template` OutboundChatTemplate — Twilio Content Template to use for outbound WhatsApp delivery.
    - `content_sid` string, required — The SID of an approved Twilio Content Template.
    - `variables` object — Template variable substitutions keyed by placeholder number.
  - `custom_variables` object — Custom prompt variables to inject into the agent configuration for this conversation.

## Response `200`

200

- OutboundChatResponse — Response returned after an outbound chat conversation is created.
  - `status` string, required — Whether the request was successful.
  - `response` OutboundChatResponseResponse, required
    - `conversation_id` string, uuid, required — Unique identifier for the created conversation.

## Other responses

- `400` — 400

---

[API](https://skmtc.dev/synthflow/apis/platform-api.md) · [All operations](https://skmtc.dev/synthflow/apis/platform-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/synthflow/platform-api/revisions/6976456ad422/schema)