4VF Platform

One framework for the full voice path.

Design real-time voice systems as connected, inspectable layers—from input and telephony through speech, reasoning, knowledge, tools and voice output.

Start Building Read the Docs

Caller Voice input

Phone / SIP Channel

STT Speech → text

AI Agent Reasoning

Tools / Knowledge Context + action

TTS Text → speech

Caller Voice output

Architecture

The system stays visible from end to end.

4VF is organized around explicit stages so teams can reason about transport, voice processing, intelligence and application actions independently.

1Voice Input

2Telephony

3STT

4AI

5Knowledge / Tools

6TTS

7Voice Output

Building Blocks

Compose the platform from clear primitives.

Each layer has one job, with interfaces designed to connect rather than obscure the rest of the stack.

Voice Agents

Configure conversational behavior, model boundaries, voice, tools and knowledge.

Workflows

Compose triggers, decisions, routing, handoffs and actions as readable logic.

Telephony

Connect numbers, SIP and programmable call paths to agent experiences.

Models

Keep reasoning configuration behind explicit provider-neutral interfaces.

Knowledge

Attach retrieval context through controlled knowledge boundaries.

Tools

Connect external actions with scoped inputs and outputs.

Observability

Inspect transcripts, runtime events, routing and outcomes together.

Agent Runtime

Put reasoning in the middle of a controlled system.

An agent can receive structured speech input, retrieve context, call tools and produce responses while workflow logic remains independently understandable.

Explore Voice Agents

Support AgentDraft configuration

System Prompt

You are a concise voice assistant. Ask one question at a time, use connected tools when needed, and hand off when the caller requests a person.

First Message

Language LLM Provider

STT Provider TTS Provider

Operational Layer

Connect calls, routes and observability.

Telephony and runtime traces sit alongside agent configuration so the production surface can evolve without turning into a collection of disconnected tools.

Explore Telephony

Telephony OperationsProduct preview

SAMPLE DATA

Active callsSAMPLE DATA

QueuedSAMPLE DATA

RoutesSAMPLE DATA

Live routingSample data

Call	Direction	Route	Status
+1 •••• 0831	Inbound	Support Agent	Connected
+1 •••• 2047	Outbound	Follow-up	Dialing
SIP / desk-17	Inbound	Human handoff	Queued
+1 •••• 9914	Inbound	Scheduling	Connected

Routing pathDemo

Incoming numberPublic entry

Conditional routeBusiness logic

Voice agentConversation

Transfer if neededHuman handoff

Build on the framework, not around it.

Explore the product areas or start with the developer documentation.

Start Building Documentation