Vapi is the Voice AI platform for developers.

Vapi AI

To enable your Vapi voice agent to send SMS messages, add the `sms` tool to your assistant's configuration. For example:

```json
"tools": [
  {
    "type": "sms",
    "metadata": {
      "from": "+15551234567"
    }
  }
]
```
This allows your agent to send texts via a configured Twilio account. **Receiving SMS is not documented as supported.**  
See the [Vapi docs for details](https://docs.vapi.ai/tools/default-tools#send-text).

Source:
- [Vapi Docs: Default Tools Send Text](https://docs.vapi.ai/tools/default-tools#send-text)