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

## New call transfer features: Preserve Caller ID, Summarization Prompt, Call Screening, and Human Detection

We've added four new options for live transfer actions, available both in the platform and via the API:

* **Preserve Caller ID** (`preserve_caller_id`) — Display the original caller's phone number to the transfer target instead of the Synthflow agent's number. Requires a number purchased through the Twilio integration inside Synthflow.
* **Summarization Prompt** (`summarization_prompt`) — Provide a custom prompt to control what information is included in the warm transfer summary briefing.
* **Call Screening** (`screened`) — Enable call screening so the transfer recipient can speak with the AI agent and accept or decline the call before being connected.
* **Human Detection** (`human_detection`) — Wait for a live human to answer before delivering the warm transfer briefing. Use with `human_detection_timeout_seconds` (30–1800s) to set the detection window.

For setup details, see [Phone Number Transfers](/call-transfers#transfer-settings). For API usage, see [Create Action](/api-reference/actions/create-action) and [Update Action](/api-reference/actions/update-action).