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By the end of this guide, you’ll have a live AI voice agent answering real phone calls. You don’t need to touch your PBX configuration, switch carriers, or write a single line of code. VoiceInfra’s no-code builder walks you through every step — from choosing an LLM to routing live calls — in under five minutes.
Every new account includes **10infreecredit∗∗—roughly100minutesoftalktimeatthebudgettier(10 in free credit** — roughly 100 minutes of talk time at the budget tier (0.07/min). No credit card required to sign up.

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Estimated Cost Per Minute

Before you begin, pick a cost tier that fits your use case. You can change models at any time.
TierRateStackExample (30-min call)
Budget$0.07/minGPT-4.1 Nano + budget voices~$2.10
Average$0.10/minGPT-4.1 Mini + Nova 3~$3.00
Premium$0.14/minGPT-4o + ElevenLabs Multilingual V2~$4.20

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Deploy Your First Agent

1

Create your account

Go to voiceinfra.ai/signup and create a free account. No credit card is required — your $10 free credit is applied instantly and covers approximately 100 minutes of calls at the budget tier.Once you’re in, you land on the main dashboard where you can see your active agents, call logs, and account balance at a glance.
2

Build your first agent

Open the AI Assistant Builder from the left sidebar and click New Assistant.
  1. Choose a template — Select from pre-built templates including customer support, appointment booking, sales qualification, after-hours reception, and more. Each template comes with pre-filled behavioral guidelines and a recommended model stack.
  2. Set your agent’s identity — Give your agent a name, write a first message (what the agent says when it picks up), and optionally add behavioral guardrails such as topics to avoid or objectives to stay focused on.
  3. Select your LLM provider — Choose from OpenAI, Anthropic, Google Gemini, Groq, or Mistral. You can use VoiceInfra’s integrated billing or connect your own API key for full cost transparency.
  4. Pick a voice — Browse 40+ voice models from ElevenLabs, Cartesia, Rime Labs, and Deepgram. Preview voices in the builder before committing.
Use dynamic variables like {{current_date}} in your first message to make responses feel contextual and timely without any extra configuration.
3

Add a knowledge base (optional)

If your agent needs to answer questions specific to your business — pricing, policies, service areas, FAQs — attach a knowledge base.In the Knowledge Base tab inside the assistant editor:
  • Upload one or more PDF documents (product guides, service manuals, FAQ sheets)
  • Paste a website URL and let VoiceInfra crawl it automatically
  • Enter raw text snippets for quick additions
Your agent uses retrieval-augmented generation (RAG) to pull accurate answers from these documents during live calls, rather than hallucinating.
Start with your most-asked FAQ document. Even a simple one-page FAQ dramatically improves accuracy on your top caller questions.
4

Connect a phone number

Your agent needs a phone number to receive or make calls. Choose one of three options:Option A — Import a Twilio or Telnyx number (recommended) Connect your existing Twilio or Telnyx account with one click. All your numbers appear in the VoiceInfra dashboard. Select the number you want to assign and pick your agent — done.Option B — Provision a new SIP number Purchase a new US phone number directly from VoiceInfra’s number provisioning feature. Numbers are ready within seconds and require no external account.Option C — Register a PBX extension This is VoiceInfra’s differentiating feature. If you have a 3CX, Yeastar, FreePBX, Asterisk, or any other SIP-compatible PBX:
  1. In your PBX admin panel, create a new SIP extension for your AI agent.
  2. Whitelist IP 51.81.221.91 in your PBX firewall — this is VoiceInfra’s SIP server address.
  3. In VoiceInfra, go to PBX Extensions, click Add Extension, and enter your PBX domain, SIP username, SIP password, and extension number.
  4. Set the call direction (inbound, outbound, or both) and save.
The extension registers within seconds and appears as online in your PBX extension list, exactly like a physical desk phone.
If SIP registration fails, double-check that 51.81.221.91 is whitelisted and that the transport protocol (TCP/UDP/TLS) in VoiceInfra matches your PBX settings.
5

Test your agent

Before sending live callers to your agent, use the built-in test tools:
  1. Test Call — Click the Test button on your agent card. VoiceInfra dials your agent and you can speak to it in real time, exactly as a caller would.
  2. Debug Panel — Watch the live transcript and tool calls as the conversation unfolds. You can see which knowledge base chunks were retrieved and what functions were triggered.
  3. Call Logs — After the test, open the call log to review the full transcript, AI-generated summary, audio recording, and any extracted data fields.
Adjust your agent’s first message, behavioral rules, or knowledge base based on what you hear, then re-test until it sounds right.
6

Go live

Assign your agent to your phone number or PBX extension (if you haven’t already), and you’re live. From this point:
  • Every inbound call to that number is answered by your AI agent — instantly, 24/7.
  • Every call generates a recording, transcript, and summary visible in your dashboard.
  • Analytics update in real time, showing call volume, duration, sentiment, and outcomes.
  • Webhooks fire on call completion, pushing structured data to your CRM, helpdesk, or any custom endpoint.
To scale up, add more agents, assign them to additional numbers or extensions, and launch outbound batch campaigns directly from the dashboard.

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Next Steps

Agent Builder

Open the no-code AI Assistant Builder and create your next agent with a template.

PBX Extensions

Learn how to register AI agents on 3CX, Yeastar, FreePBX, and any SIP-compatible PBX.

API Reference

Trigger outbound calls, receive webhook events, and build custom integrations with the REST API.