---
title: "Send context to an active voice call"
description: "Served by the standalone Voice API. Requires a Bearer session for a workspace owner/admin/manager when VOICE_AI_TELEPHONY_TURN_CONTROL_V2 is enabled. Legacy flag-off access is preserved. Internal callers may instead send X-Voice-Service-Time (Unix milliseconds) and X-Voice-Service-Signature (hex HMAC-SHA256). The signature binds the method, full route including workspace, and JSON body, and expires after 60 seconds. Existing route-specific validation still applies."
---

> Documentation Index
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Path: Channel Automation API › Workspaces

`POST /api/workspaces/{workspaceId}/voice-ai/calls/{callSid}/context`

Served by the standalone Voice API. Requires a Bearer session for a workspace owner/admin/manager when VOICE_AI_TELEPHONY_TURN_CONTROL_V2 is enabled. Legacy flag-off access is preserved. Internal callers may instead send X-Voice-Service-Time (Unix milliseconds) and X-Voice-Service-Signature (hex HMAC-SHA256). The signature binds the method, full route including workspace, and JSON body, and expires after 60 seconds. Existing route-specific validation still applies.

## Authentication

- `BearerAuth`, http, header `Authorization`, format `JWT`

## Path parameters

- `workspaceId` (`post/api/workspaces/workspaceId/voice-ai/calls/callSid/context.path.workspaceId`; string, required)
- `callSid` (`post/api/workspaces/workspaceId/voice-ai/calls/callSid/context.path.callSid`; string, required)

## Header parameters

- `X-Voice-Service-Time` (`post/api/workspaces/workspaceId/voice-ai/calls/callSid/context.header.X-Voice-Service-Time`; string, optional) — Required with service signature; Unix milliseconds.
- `X-Voice-Service-Signature` (`post/api/workspaces/workspaceId/voice-ai/calls/callSid/context.header.X-Voice-Service-Signature`; string, optional) — Service request HMAC; alternative to Bearer authentication.

## Request body

- `content` (`post/api/workspaces/workspaceId/voice-ai/calls/callSid/context.content`; string, optional) — Context text; required, capped at 1200 characters.
- `mode` (`post/api/workspaces/workspaceId/voice-ai/calls/callSid/context.mode`; string, optional) — silent or respond; defaults to silent.

## Example request

```json
{
  "content": "string",
  "mode": "string"
}
```

## Code samples

### cURL

```bash
curl --request POST \
  --url 'https://api.channelautomation.com/api/workspaces/<workspaceId>/voice-ai/calls/<callSid>/context' \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "content": "string",
  "mode": "string"
}
'
```

### TypeScript

```typescript
const url = 'https://api.channelautomation.com/api/workspaces/<workspaceId>/voice-ai/calls/<callSid>/context';
const options = {
  method: 'POST',
  headers: {'Content-Type': 'application/json', Authorization: 'Bearer <token>'},
  body: JSON.stringify({content: 'string', mode: 'string'})
};

fetch(url, options)
  .then(res => res.json())
  .then(json => console.log(json))
  .catch(err => console.error(err));
```

### Python

```python
import requests

url = "https://api.channelautomation.com/api/workspaces/<workspaceId>/voice-ai/calls/<callSid>/context"

payload = {
    "content": "string",
    "mode": "string"
}
headers = {
    "Content-Type": "application/json",
    "Authorization": "Bearer <token>"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)
```

## Responses

### 200

Successful operation

### 400

Invalid call or preview parameters

### 401

Missing or invalid session

### 403

Workspace owner/admin/manager required

### 404

Requested resource not found

### 409

Call is not in a state permitting this operation

### 500

Operation failed

### 503

Access verification or service unavailable


Source: https://developer.channelautomations.com/api/post-api-workspaces-workspace-id-voice-ai-calls-call-sid-context/index.md