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VoiceInfra puts AI voice agents on the phone system you already have. Agents register as ordinary SIP extensions on 3CX, Yeastar, FreePBX, Asterisk, or any PBX that speaks SIP. From your phone system’s point of view nothing unusual has happened: an extension is registered, and calls route to it like any other. No carrier to change, no number to port, no hardware to replace. Callers get a natural conversation in 30+ languages at any hour; you get a recording, a transcript, a summary, and structured data for every call.
VoiceInfra works alongside your PBX, SBC, and telephony rather than replacing them. You keep your carrier, your numbers, and your routing rules. Agents appear as new extensions.

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How a call flows

1

The caller reaches your number

A number you provisioned with VoiceInfra, one imported from Twilio or Telnyx, a WhatsApp Business number, a website widget, or an extension on your own PBX. VoiceInfra answers immediately — no hold music, no menu to press through.
2

Your agent holds the conversation

It opens with your greeting, works out what the caller needs using whichever language model you chose, and answers from your knowledge base — documents you uploaded, or pages crawled from your website.
3

Actions run while the caller is still on the line

Updating a CRM record, booking an appointment, sending a Teams message, querying an internal API, or transferring to a human. Nothing is deferred to after the call.
4

The call becomes a record

Every call ends with a transcript, an AI-generated summary, any structured data the agent collected, and a cost breakdown — all on the call log.

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Key concepts

A handful of terms recur throughout these docs.
The AI that handles a conversation — its greeting, its instructions, the model and voice it uses, and everything it has access to. Most of the platform exists to configure, test, and observe agents.
A branching conversation instead of a single prompt. A workflow is a graph of nodes — conversation steps, tool calls, transfers, knowledge lookups — connected by edges that decide where to go next. An agent either runs a prompt or runs a workflow, not both.
How a call reaches an agent. A number is a phone line; an extension is a registration on your own PBX; WhatsApp and the website widget are additional channels. Any of them can be pointed at an agent, and one agent can serve several.
The documents an agent answers from — uploaded files, or pages crawled from your site. Attached to agents, shared across as many as you like.
Two ways to give an agent access to something outside VoiceInfra. A function calls an HTTP endpoint you define. An MCP server exposes a set of tools over the Model Context Protocol. Both are attached to agents and called during the conversation.
Edits never reach callers until you publish. Test Call uses the draft; live calls use the published version. See Publishing & Versions.
The container for your agents, numbers, knowledge, team, and billing. You can belong to more than one, with a different role in each. See Workspaces and roles.
The built-in AI builder. Describe what you want in plain language and Sculptor configures it, showing every change before it applies. See Sculptor.

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What makes VoiceInfra different

Traditional IVR and standalone voice bots each fall short in their own way. VoiceInfra combines the telephony integration of a PBX with the intelligence of modern language models. VoiceInfra runs its own SIP infrastructure rather than reselling an external WebRTC provider, which keeps call completion costs down.

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Who uses VoiceInfra

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Telecom operators and MSPs

If you already manage PBX infrastructure for business customers, VoiceInfra fits into your offering with no infrastructure change. At scale it talks to your SBC or core network over standard SIP signalling, with TCP, TLS, or UDP transport and SRTP for media.

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Contact centres

Handle every call without hold queues, including the ones that arrive at 3am. Agents qualify callers, resolve common requests, and hand to a person when the conversation needs one — with the context briefed across.

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Businesses automating inbound and outbound calls

From dental practices booking appointments to estate agents following up leads. Inbound agents answer, qualify, and route. Outbound agents call from your CRM, deliver a message, and hand warm leads to your sales team the moment interest appears.

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Websites and apps

The web widget lets visitors call, chat, or reach a human without leaving your site.

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Where to go next

Quickstart

Build your first agent and take a live call.

Build with Sculptor

Describe the agent you want and review what it builds.

Connect your phone system

Register agents as extensions, or bring your own numbers.

Use it from your own tools

The MCP server, the REST API, and OAuth.