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The AI phone system

The phone system with its own wires underneath, not a rented API on top.

Zumu runs its own SIP-optimized infrastructure underneath every call. Connect it the classic way, with a SIP trunk you already have, or the modern way, with an API-native carrier. Either way, Zumu still buys and configures the number, builds the call flow, and keeps a next move ready when the first branch does not answer.

  • Numbers live in minutes
  • Your carrier or ours
  • IVR that builds itself
  • Extensions for your people
Book a demoSee the call flow
Inbound routing paths
5
Hops checked before a call is allowed to ring
4
Node types in the call-flow builder
8

Counted from the call-flow schema and the routing verifier, not rounded for the page.

Every call runs through this flow.

Call flow8 node types
trigger

Inbound call

A number you bought or brought rings in

receptionist

IVR menu

Press 1, 2, or 3

DTMF · 1
phone_transfer

Front desk

Rings your existing line

DTMF · 2
agent

AI receptionist

Answers and listens for intent

sip_transfer

Dispatch, ext. 214

Warm handoff to a person

DTMF · 3 · fallback
voicemail

Voicemail

Transcribed, not a black box

The DTMF · 2 path above is the one actually animating. Every branch in a real flow carries the same fallback discipline, not just the one on the poster.

A desk phone and headset lit at dusk, the physical end of a call flow that started as a number in a dashboard
Where the flow ends up

The stack underneath

From carrier to answer, every layer is ours.

A complete, owned real-time telephony stack, not a thin wrapper on a voice API.

  1. 01

    Carrier

    SIP / PSTN

    The number you already have, or one we provision, arriving over classic SIP trunking or a modern API-native carrier.

  2. 02

    SIP edge

    Our infrastructure

    Our own SIP-optimized infrastructure terminates the call and streams the audio, live, the moment it lands.

  3. 03

    Media engine

    Real-time audio

    Noise handling, voice-activity detection, and barge-in run here, on the raw audio, before a word reaches the model.

  4. 04

    AI runtime

    The agent

    Speech recognition, turn-taking, the language model, its tools, and text-to-speech, all in the same session.

A real phone agent. Not a chat widget with a microphone.

How the wiring works

A number is not a feature. It is a pipeline.

Buying a number, choosing a carrier, staffing an extension, and keeping a route alive are four separate jobs that usually live in four separate tools. Here they are one schema.

  • Numbers live in minutes

    Buying a number runs a four-step pipeline: buy it from Twilio, assign it to a SIP trunk, create the matching trunk on the voice side, and save the routing config. Twilio's webhook keeps the number synced after that, automatically.

  • Bring your own carrier

    Zumu runs its own SIP-optimized infrastructure underneath every number. Connect it the classic way, with a SIP trunk you already have a contract with, or the modern way, with an API-native carrier like Twilio. The call flow behind the number does not know or care which one it is.

  • Extensions for your people

    A SIP extension is a real seat, not a placeholder: agent, supervisor, or admin, with its own voicemail, and an optional link to an AI agent that can staff the extension when nobody is at the desk.

  • Routing that heals itself

    A four-hop verifier checks the path before a call is allowed to ring anything. A heartbeat catches an agent that stopped responding mid-shift. A call that connects and then dies gets diverted instead of going to dead air, and every number can carry its own fallback for the day the primary path is down.

The routing vocabulary

5

Inbound routing paths: straight to an agent, a fixed IVR, the AI receptionist, a flow node, or the fallback number that catches what is left.

8
Node types in the call-flow builder, from a trigger to a flow transfer
Retry + fallback
What every DTMF branch carries: a retry limit and a landing spot when nobody presses a key

These are the shapes in the schema, not a rounded number for the page. If a call reached your team, it reached it through one of five paths.

Questions

The wiring, answered plainly

Buying a number runs a four-step pipeline: it is purchased from Twilio, assigned to a SIP trunk, matched to a trunk on the voice side, and the routing config is saved. From there, a webhook keeps the number in sync automatically, so it does not quietly drift out of date the way a manually wired number can.

Book a demo

See your own numbers in a call flow

Bring a number you already own, or let us provision one live. We will build the IVR, wire the fallback, and show you exactly where a call goes when the first branch does not answer.

Book a demoTalk to sales
  • No credit card for the demo
  • Bring a SIP carrier you already use, if you have one
Zumu Telephony | The AI Phone System Behind Your Numbers