> 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 for multilingual agents

![Synthflow TTS selected as the voice model on a Multilingual agent](https://storage.googleapis.com/granular-changelog/doc-images/multilingual_synthflow_tts.png)

Agents set to **Multilingual** can now use [Synthflow TTS](/voice-configuration#synthflow-tts) as their voice model or fallback. One voice covers the whole conversation, including when the caller switches language mid-call.

## Custom action response time

![Response time on a custom action in the Actions tab of call details](https://storage.googleapis.com/granular-changelog/doc-images/custom_action_response_time.png)

[Call details](/logs#call-logs) now shows the response time of every custom action. Open a call, check the **Actions** tab, and find the slow endpoint behind a long silence.

## Call quality metrics on every call

![Call quality section in the Telephony tab of call details](https://storage.googleapis.com/granular-changelog/doc-images/call_quality_telephony.png)

The **Telephony** tab now reports [call quality](/sip-call-ladder#call-quality) for every call, so you can rule out the network without pulling a PCAP. The same measurements are on the [Calls endpoints](/api-reference/platform-api/calls/list-calls).