Voice agents
on a single line.
MultilineAI is the developer platform for production voice. Sub-500ms turn-taking, 40+ languages, native telephony, and a runtime that scales to millions of concurrent calls.
- Free 60 minutes / month
- No credit card
- BYO model & voice
- SOC2-aligned
Trusted by teams shipping voice at scale
// platform
Everything the call needs.
Nothing it doesn't.
Sub-500ms turns
End-to-end voice loop optimized for natural turn-taking with barge-in and interruption handling.
40+ languages
Multilingual ASR, TTS and reasoning. Switch language mid-conversation without dropping context.
BYO model
Plug any LLM — OpenAI, Anthropic, Gemini, or your own private model behind a URL.
Native telephony
Inbound and outbound calls, SIP trunking, and warm transfer to a human in one API.
Studio-grade voices
Cloned, branded or stock voices with emotion control and SSML when you need it.
Built for devs
TypeScript SDK, webhooks, deterministic tests, and a CLI that mirrors your prod config.
// quickstart
Launch a voice agent in seven lines.
Define the agent, pick a voice, attach tools. We handle the audio pipeline, telephony, observability and scaling.
- Streaming TTS + ASR included
- Function calling with retries & timeouts
- Recordings, transcripts & analytics out of the box
import { Multiline } from "multilineai";
const ml = new Multiline(process.env.ML_KEY);
await ml.agents.create({
name: "front-desk",
voice: "ember",
model: "gpt-4o-mini",
prompt: "You're the friendly front desk at Atlas Health.",
tools: ["calendar.book", "calendar.cancel"],
phoneNumber: "+14155550142",
});// use cases
Built for every line that rings.
Healthcare
Appointment scheduling, intake, refills — HIPAA-aware deployments.
Commerce
Order status, returns, and AI sales agents that close.
Logistics
Driver dispatch, ETA confirmations, automated follow-up.
Financial
KYC, collections, and account servicing with audit-ready logs.
Pick up the line.
Start free. No card. Your first agent goes live in under five minutes.