How Voice Nexus Works

From phone number to live AI agent in minutes. Here's the full call lifecycle.

The Call Lifecycle

  1. 1

    Create your account

    Sign up at vnsportal.voiceelements.com. Setup is self-service from there. Step-by-step guide →

  2. 2

    Choose how to configure the agent

    Build and publish a managed agent in VnsPortal, or host dynamic CallStart/CallEnd webhooks that return configuration for each call.

    Managed in VnsPortal → Best for most agents. Start from a QuickStart template; no webhook service to host. Dynamic webhooks → For per-call decisions driven by your own application.
  3. 3

    Connect a phone number or place a test call

    Get a phone number in VnsPortal and point it at your agent, or place an outbound test call.

  4. 4

    VNS opens the Realtime session

    VNS applies the published agent configuration or the configuration your CallStart webhook returned, and connects the caller to the AI.

  5. 5

    The agent uses tools

    Built-in VNS tools (transfer, SMS, call info), your HTTP tools, or MCP tools — with results fed back into the conversation.

  6. 6

    VNS completes the call

    VNS ends the call and records the configured CallEnd evidence — timing, status, transfers, and diagnostics.

Managed AI Voice Agent Flow

When the number is assigned to a published VnsPortal agent.

  1. 1

    Call Arrives

    An inbound call reaches a number assigned to your published agent, or you send an outbound test call from the Phone Numbers page.

  2. 2

    VNS Supplies the Configuration

    VNS serves the published revision of your agent instead of calling a CallStart webhook, including any call flow announcements you configured.

  3. 3

    AI Conversation

    The agent talks with the caller and uses its configured tools, transfers, and SMS until the call completes.

Get Started in VnsPortal

Developer-managed call flow

Inbound Call Flow

  1. 1

    Call Arrives

    An inbound call or WebRTC session enters the Voice Elements Cloud Platform and is routed to Voice Nexus Service.

  2. 2

    CallStart Webhook

    VNS sends an HTTP POST to your CallStart endpoint with session details (caller ID, DID, session GUID). Your endpoint returns instructions, model config, tools, and time limits.

  3. 3

    AI Session Begins

    VNS establishes a WebSocket session with OpenAI Realtime voice and supplies your returned instructions. The caller hears a natural AI voice.

  4. 4

    Tool Execution

    During the conversation, the AI can invoke tools — your APIs, CRM lookups, scheduling, or built-in VNS tools like call transfer. Results are fed back into the conversation.

  5. 5

    Call Ends

    When the call completes, VNS sends a CallEnd webhook with timing, status, and diagnostic data.

Developer-managed call flow

Outbound Call Flow

  1. 1

    API Request

    Your system sends a dial request to the VNS Web API with the destination number, caller ID, and caller name.

  2. 2

    Session Created

    VNS returns a session token, triggers your CallStart webhook (marked as outbound-initiated), and places the call.

  3. 3

    AI Conversation

    Once answered, the session proceeds like an inbound AI call with full tool and transfer support.

Build with the API

Ready to Automate Your Phone Lines?

Create your account in VnsPortal and set up your first agent from a template today — or book a live demo and we'll walk you through it.

Get Started Book a Demo

Questions first? Contact sales