> ## 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.

<Info>
  **Enterprise Feature** - SMS is only available on Enterprise plans.
</Info>

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](/api-v1/post/sms-send), 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

<ParamField header="authorization" type="string" required>
  Your API key for authentication.
</ParamField>

<ParamField header="idempotency-key" type="string" required={false}>
  Safe retries: repeated requests with the same key do not send a second message.
</ParamField>

### Path Parameters

<ParamField path="conversation_id" type="string" required>
  The conversation to send on.
</ParamField>

### Body Parameters

<ParamField body="message" type="string" required>
  The text to send. Up to 1600 characters.
</ParamField>

<ParamField body="sender" type="string" required={false}>
  `"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.
</ParamField>

### Response

<ResponseField name="data.message_id" type="string">
  Use with delivery status webhooks.
</ResponseField>

<ResponseField name="data.human_handoff_active" type="boolean">
  Whether the conversation is currently handed off.
</ResponseField>

<ResponseExample>
  ```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
  }
  ```
</ResponseExample>