December 4th, 2025
What's New: Synthflow Chat, Simulations 2.0, and Multi-Agent Systems
This month marks an exciting milestone for Synthflow. We’re introducing Synthflow Chat, expanding our platform beyond voice so your agents can now handle written conversations with the same intelligence, logic, and infrastructure you rely on for calls.
This release also brings major upgrades for enterprise teams, including Simulations 2.0 for automated regression testing, Multi-Agent Systems that are now more powerful with reusable subflows, full GPT‑5.1 support, and enhanced platform controls designed for large-scale deployments.
And this is just the beginning. Over the coming months, we’ll continue expanding how and where your agents can operate, moving toward a fully unified, omnichannel experience.
Synthflow Chat: One Agent. One Platform. Every Channel.
Some customers call. Others prefer chat. Stop managing separate agents for separate channels. Synthflow Chat unifies your customer experience.
Your agents now handle written conversations with the same intelligence as voice, booking appointments, updating your CRM, and solving problems instantly.
Build agents once with our visual flow designer and use them across voice and chat. Deploy in minutes by embedding our widget or integrating on your terms via the API.
Unified Agent Model: Use your existing voice agents for chat. No need to maintain separate agents.
Embeddable Widget: Add a chat widget to your site with a simple code snippet.
API Chat Sessions: Programmatically manage chat interactions for custom integrations.
Unified Logging: Review chat transcripts alongside call logs in a single dashboard.
Multi-Agent Systems: Modularize Your Logic with Subflows
We’ve made building modular, scalable agents even easier. Subflows act as specialized, reusable agents that can be activated by specific intents (e.g., "Caller mentions severe symptoms"), allowing you to organize your conversation graph efficiently.
With the new Return to Main Flow node, you have explicit control over when a subflow hands control back. Once the subflow completes its task, control returns seamlessly to the main agent exactly where it left off.
Scalable Logic: Break complex agents into manageable, reusable components.
Seamless Hand-offs: Delegate specific tasks to subflows and return to the main conversation flow automatically.
Read the Multi Agent Systems documentation
Simulations 2.0: Ship with Confidence using Automated Regression Testing
Testing Voice Agents is notoriously difficult. That’s why in Simulations 2.0, we are introducing test suites—making it easy to group related test cases and run them in batches. Simulations are now dramatically faster and more cost-effective to run, enabling you to automate regression testing for Voice AI.
Instead of manually calling your agent to check for issues after every change, you can now use automated test suites to verify that your agent still performs exactly as expected.
Test Suites: Group related test cases and run them together, with improved speed and lower cost.
Auto-Generated Tests: Automatically generate comprehensive test cases based on your agent's prompts.
Detailed Analysis: Get pass/fail breakdowns based on specific success criteria.
Read the Test Center documentation
GPT-5.1: The Latest Intelligence, Available Instantly
We are committed to making the latest models available within days of release. Ever since it was released you can use GPT-5.1, the most advanced model from OpenAI, to drive your agents.
GPT-5.1 brings unprecedented conversational intelligence to voice AI. To ensure you get the most out of the model, our prompting guide provides essential strategies for crafting optimal interactions.
Read the GPT 5.1 Prompting Guide
Enterprise & Platform Updates
Zero-Downtime Voice Synthesis Infrastructure
We have strengthened our voice infrastructure to ensure your agents are always ready to speak. We now support multiple high-quality voice providers with automatic failover.
If your chosen voice experiences an outage, our system will instantly switch to a perceptually similar voice from a backup provider. The transition is seamless, and the person on the other side of the line won't even notice, ensuring your operations continue without interruption.
Synchronize Call Data with X-EI SIP Headers
For our enterprise partners, the X-EI SIP header allows you to pass critical metadata—such as internal Call IDs, CRM records, or diversion history—directly through SIP headers. This ensures downstream systems and Synthflow logs stay perfectly synced.
Subaccount Management
Admins can now directly access and review logs within subaccounts for faster troubleshooting.
Extended Call Duration
We have increased the maximum call duration to 100 minutes, supporting longer consultations, complex support triage, and extended interview sessions.