> For a complete page index, fetch https://docs.synthflow.ai/llms.txt. For full documentation content, fetch https://docs.synthflow.ai/llms-full.txt.

## Synthflow TTS voice model

Synthflow TTS is now available as a [voice model option](/voice-configuration#synthflow-tts) in the agent editor. It delivers low-latency, natural-sounding speech across 32 languages with 12 built-in voices.

The [GET /voices](/api-reference/platform-api/voices/get-voices) endpoint now supports `search` and `provider` query parameters for filtering, and voice responses include `provider`, `gender`, and `languages` fields.

![](https://storage.googleapis.com/granular-changelog/doc-images/changelog_synthflow_tts.png)

## Outbound number pooling for agents

You can now assign multiple outbound phone numbers to one agent and choose the caller ID for each outbound call. See the [Outbound Number Pooling](/outbound-number-pooling) guide.

| Endpoint                                                                                                                   | Change                                                                                    |
| :------------------------------------------------------------------------------------------------------------------------- | :---------------------------------------------------------------------------------------- |
| [**GET /assistants/\{model\_id}**](/api-reference/platform-api/agents/get-assistant)                                       | Returns `attached_phone_numbers` with each attached number's `number`, `sid`, and `slug`. |
| [**PUT /assistants/\{model\_id}/phone\_numbers**](/api-reference/platform-api/agents/attach-phone-numbers-to-assistant)    | Attaches multiple outbound numbers using `phone_numbers` or `phone_number_slugs`.         |
| [**DELETE /assistants/.../\{phone\_number\_slug}**](/api-reference/platform-api/agents/detach-phone-number-from-assistant) | Detaches one outbound number from the agent.                                              |
| [**POST /calls**](/api-reference/platform-api/calls/voice-call)                                                            | Accepts `from_phone_number` to select the outbound caller ID for that call.               |

## Knowledge Base API: New Endpoint

You can now update existing knowledge base sources by source ID. The endpoint supports `name`, `url` for `link` and `file` sources, and `content` for `text` sources.

| Endpoint                                                                                                   | Change                                              |
| :--------------------------------------------------------------------------------------------------------- | :-------------------------------------------------- |
| [**PUT /sources/\{source\_id}**](/api-reference/platform-api/knowledge-bases/update-knowledge-base-source) | Updates the source `name` and type-specific fields. |