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Developer-first Voice AI framework

Build Better Voice AI.

The framework for intelligent conversations.

Build, deploy and scale real-time AI voice agents across phone, web and applications — without managing complex voice infrastructure.

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Real-time voice Visual workflows Telephony Developer APIs
4VF signal path
SYSTEM VIEW
streaming events programmable routing tool boundaries
Architecture

A voice system you can reason about.

4VF organizes the real-time path from caller input to reasoning, tools, speech output and routing as explicit building blocks.

Real-time voice path
SYSTEM VIEW
streaming events programmable routing tool boundaries
Live Voice Demo

Watch the conversation and the system at the same time.

This interactive demo pairs a simulated conversation with transcript and technical events so the system state stays visible.

Speech states Runtime events Tool activity
Support Agent Connected
00:24
Caller speaking
TranscriptLIVE DEMO
Caller

I need to update the delivery window for my order.

Agent

I can help with that. I’ll check the order details and available windows.

Caller

Tomorrow afternoon would work best.

Technical eventsDemo
Speech Detected
Model Request
Tool Called
Response Generated
TTS Started

Interactive product simulation with representative transcript and runtime events.

Core Platform

Everything the voice application needs to stay connected.

Configure the conversation, orchestrate the path, connect telephony and inspect what happened—without collapsing the system into a black box.

Voice Agents

Configure real-time conversational behavior, model settings, voices, knowledge and tools in one place.

Visual Workflows

Compose routing logic, conditions, tool calls, handoffs and reusable conversation flows visually.

Telephony

Bridge intelligent agents to phone numbers, SIP and programmable inbound or outbound call paths.

Observability

Inspect transcripts, technical events, timing and call outcomes without hiding the underlying system.

Workflow Builder

Route conversations visually.

Compose triggers, speech, agent behavior, conditions, tools, knowledge and handoff as a readable workflow your team can reason about.

Branch on intent or context

Model decision points as explicit workflow logic.

Connect tools and knowledge

Keep business actions and retrieval visible in the flow.

Test before publish

Treat the public preview as a product concept, not a complete execution engine.

Explore Workflows
Customer routingMarketing preview
Incoming CallTrigger
STTVoice input
AI AgentReasoning
ConditionRoute intent
Knowledge BaseRetrieve
CRM / CalendarTool action
Transfer CallHandoff
TTSVoice output
✓
End CallComplete
100%
Voice Stack

Bring the voice pipeline into one framework.

Keep speech recognition, reasoning and speech synthesis as clear provider-neutral layers that can evolve independently.

Input

Speech-to-Text

Turn live voice input into structured text for downstream reasoning.

Reasoning

LLM Layer

Coordinate prompts, context, tools and knowledge through a provider-neutral model boundary.

Output

Text-to-Speech

Render generated responses back into natural speech through a provider-neutral voice boundary.

Telephony

Connect intelligent conversations to real call flows.

Model numbers, SIP, inbound and outbound paths, routing, queues, DTMF, transfers and human handoff from the same light, technical product system.

Explore Telephony
Telephony OperationsProduct preview
SAMPLE DATA
Active callsSAMPLE DATA
12
QueuedSAMPLE DATA
3
RoutesSAMPLE DATA
8
Live routingSample data
CallDirectionRouteStatus
+1 •••• 0831InboundSupport AgentConnected
+1 •••• 2047OutboundFollow-upDialing
SIP / desk-17InboundHuman handoffQueued
+1 •••• 9914InboundSchedulingConnected
Routing pathDemo
Incoming numberPublic entry
Conditional routeBusiness logic
Voice agentConversation
Transfer if neededHuman handoff
Integrations

Let voice systems act on the rest of your stack.

Connect generic categories such as CRM, calendars, databases, automation, webhooks, APIs and custom tools through explicit integration boundaries.

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Developer Experience

Readable primitives for teams that ship software.

Work with familiar API, event and transport concepts while keeping illustrative examples clearly separated from final contract guarantees.

REST API

Model voice resources and operations through conventional HTTP boundaries.

SDKs

Wrap common client and server integration patterns with typed developer ergonomics.

WebSocket

Support event-oriented real-time interaction where streaming transport is appropriate.

Webhooks

Notify your systems about lifecycle and workflow events at configured endpoints.

Developer Overview
Illustrative TypeScript ILLUSTRATIVE 
// Illustrative architecture example
const agent = await voiceFramework.agents.create({
  name: "Support Agent",
  language: "en",
  tools: [lookupOrder, updateWindow]
});

await voiceFramework.calls.route({
  target: agent.id,
  handoff: "human-if-requested"
});
Observability

Trace the conversation beyond the transcript.

Inspect voice states, model activity, tool calls and routing decisions as one execution story.

Conversation timeline

Align transcript context with runtime events.

Tool visibility

See where external actions enter the conversation path.

Outcome context

Keep routing and completion states readable after a call.

Use Cases

A framework for task-focused conversations.

Apply the same voice building blocks across customer operations, scheduling, support and application experiences.

Customer Operations

Automate structured conversations while preserving routing and human escalation paths.

Scheduling

Connect conversational intent to calendars, availability and application logic through tools.

Lead Qualification

Collect structured context and route conversations based on configured criteria.

Support Triage

Use knowledge and workflow logic to understand intent before handing off when needed.

Voice Interfaces

Add real-time conversational access to applications, services and connected systems.

Internal Operations

Create task-focused voice experiences for repeatable team workflows and information access.

Enterprise

Keep the boundaries explicit as systems grow.

Connect channels, 4VF framework components and your own systems through clear interfaces. Deployment, security and operational requirements can be scoped with the team for your environment.

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Pricing Preview

Start with the commercial structure that fits your stage.

Start with usage-based options for development and production workloads, with custom options for enterprise needs.

Developer

Usage Based

For development, testing and prototypes.

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Production
Growth

Usage Based

For production voice workloads.

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Enterprise

Custom Pricing

Custom infrastructure and support options.

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4VF — Voice Framework

Build Better Voice AI.

Start with a framework designed to keep conversations, routing, tools and voice infrastructure understandable.

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