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Voice AI ClientsCartesia Line Agents

Overview

Cartesia Line Agents in VoxEngine
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For the complete documentation index, see llms.txt.

Benefits

The native Cartesia module connects Voximplant calls to Cartesia Line Agents for real-time, speech-to-speech conversations. This allows one agent design to power calls across SIP trunks, WhatsApp, PSTN numbers, and app users while VoxEngine keeps call routing and control.

Capability and feature highlights:

  • Connect inbound and outbound calls to one Cartesia Line Agent
  • Bi-directional media streaming with telephony-ready audio format support
  • Barge-in support via clear events and media buffer control
  • Real-time agent events for ACK, custom metadata, DTMF, and diagnostics

Demo video

Cartesia Line Agents demo:

Video link: Cartesia Line Agents demo

Architecture

Cartesia Line Agents architecture

Prerequisites

Development notes

  • Native VoxEngine module: load require(Modules.Cartesia) and create a Cartesia.AgentsClient via Cartesia.createAgentsClient({ apiKey, agentId, cartesiaVersion, ... }).
  • Line Agent → VoxEngine coordination: handle AppEvents.HttpRequest in your scenario to process POST messages sent by your Cartesia Line script for tool-call orchestration and routing decisions.
  • VoxEngine → Line Agent configuration: pass telephony context and callback endpoints to Line using the metadata object in client.start({ ... }) so the agent can request out-of-band actions from VoxEngine.
  • Barge-in and turn-taking: interruption behavior between caller/callee and the agent is managed by the Line Agent runtime; no additional VAD or turn-taking configuration is required in VoxEngine.
  • Telephony tools for Voximplant-controlled routing: Line built-ins like end_call and transfer_call are designed for Line-native calling flows. For Voximplant-owned flows (warm transfer, SIP handoff, post-call survey), define passthrough tools in Line that signal VoxEngine out-of-band, then execute the telephony action in VoxEngine.

The Function Calling example demonstrates how to use the HTTP callback pattern for Line → VoxEngine control. See the Cartesia module API reference for all methods and events.

Examples

Voximplant

Cartesia