June 4th, 2025
What's New in Synthflow: Warm Transfer with Context, Variables in Inbound Webhook
We’ve added some great new features to Synthflow this May — including warm transfers with helpful context, improved SIP routing, and clearer error handling — all designed to help you work faster and troubleshoot smarter.
We’ve expanded our call transfer capabilities. You can now performWarm Transfers with a Contextual Summary allowing your AI agent to hand off calls to a human agent with a real-time summary of the conversation. This ensures smoother transitions and better customer experiences.
We now support:
Cold Transfer: Immediate, no message is played to the human receiving the call.
Warm Transfer with Message: You can configure a hard coded message to be played to the human receiving the call.
Warm Transfer with Contextual Summary: Our AI will automatically summarise the conversation between your customer and Synthflow when handing over to your human agent.
Read more in the documentation.
Want to learn how to make the most of warm transfers? Join our special live session with Kevin on Friday June 6.
In this live session, Kevin will guide you through building flows that pass context before your Voice Agent transfers a client to a team member.
You can now use Diversion headers to route inbound SIP calls with greater precision and context.
Unlike standard SIP headers, Diversion headers tell you where the call came from and why it was redirected. That’s crucial for call forwarding, transfers, and any flow where caller history matters.
Previously, routing relied on static SIP headers and rigid logic. Now, Diversion headers give you the flexibility to steer each call to the right Voice AI Agent, using richer context—all without breaking SIP protocol.
Note: Diversion headers work only for inbound calls.
Read more in the documentation.
Inbound Webhook with Custom Variables: customize inbound call behavior with dynamic variables. Use your Inbound Call Webhook to automatically manage call flows and apply context-specific logic.
Read the Inbound Webhook documentation.
Custom Action Messaging Control: We’ve added API support to give developers more control over how custom action messages behave. You can now:
Choose between LLM-generated or hardcoded messages
Set fallback messages for failed or delayed actions
Read more in the documentation.
We've enhanced how Twilio error codes are displayed in the dashboard. You can now view the End Call Reason to quickly identify if an issue was related to your Twilio setup.
In Case You Missed It: IVR Handling
Until now, outbound agents couldn’t get past IVR menus. When a call reached a phone tree — “Press 1 for sales, 2 for support” — the agent had no way to respond. That meant stalled flows, missed connections, and broken automation.
We’ve fixed that. With IVR Handling, outbound agents can now simulate keypresses to navigate DTMF‑based IVR systems automatically. Whether it’s a single prompt or a multi‑step phone menu, agents can now complete the flow end‑to‑end.
Have you had a chance to try IVR Handling yet? If not, check out our brand‑new tutorial video and see it in action: