> ## Documentation Index
> Fetch the complete documentation index at: https://docs.bland.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Send Message on Conversation

> Send a message on an existing conversation from the agent number, as a human rep or as the agent.

> [!NOTE]
>
> **Enterprise Feature** - SMS is only available on Enterprise plans.

Sends a fixed message on a specific conversation. The message goes out from the conversation's agent number to the user's number, is stored on the thread, and fires the message webhook with `sender` set to `"HUMAN"` (default) or `"AGENT"`.

Unlike [Send SMS](https://docs.bland.ai/api-v1/post/sms-send.md), this is keyed on the conversation ID rather than the number pair, so it always lands on this thread, including while the conversation is handed off to a human.

### Headers

**authorization** `string` *required*

Your API key for authentication.

**idempotency-key** `string`

Safe retries: repeated requests with the same key do not send a second message.

### Path Parameters

**conversation\_id** `string` *required*

The conversation to send on.

### Body Parameters

**message** `string` *required*

The text to send. Up to 1600 characters.

**sender** `string`

`"HUMAN"` (default) attributes the message to a human rep in the transcript and webhooks. `"AGENT"` attributes it to the agent, the same as `agent_message` on Send SMS.

### Response

**data.message\_id** `string`

Use with delivery status webhooks.

**data.human\_handoff\_active** `boolean`

Whether the conversation is currently handed off.

```json 202 Accepted theme={null}
{
  "data": {
    "status": "processing",
    "message": "Message accepted for delivery",
    "conversation_id": "8f1c2a4e-1b7d-4f2a-9c1e-2d3f4a5b6c7d",
    "sender": "HUMAN",
    "message_id": "b7e2c1d0-3f4a-4b5c-8d9e-0f1a2b3c4d5e",
    "human_handoff_active": true
  },
  "errors": null
}
```


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