April 10, 2026 | Synthflow

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. For API usage, see Create Action and Update Action.

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. For API usage, see Create Action and Update Action.