Healthcare
Appointment reminders and confirmations.
A Fourstack product · Voice AI platform
Vox
AI agents that make and answer real phone calls.
Vox lets a team describe a phone agent in a browser — its voice, its language, its opening line, the questions it must cover — attach a knowledge base built from their own documents, then place a real test call to their own number before anyone else hears it. When it sounds right, production call volume points at the same agent, and every completed call returns a full transcript plus a webhook into your own systems.
Access is granted per workspace — we set you up and walk through your first agent with you.
vox.fourstack.in / agents
Agent
Renewals — Hindi
- Engine
- OpenAI Realtime + Cartesia
- Voice
- Aarav
- Language
- Hindi
- Dialer
- Smartflo
Questions, in order
- 1Confirm I'm speaking with {name}
- 2Is the policy still active at this address?
- 3Would you like to renew for another year?
- 4Shall I send the payment link on WhatsApp?
Policy handbook v4attached
Test call to my phone
Rings your number on real telephony
01
Build
A linear question list when the call is a script, a drag-and-drop flow canvas when the call branches. Same voices, same knowledge, same telephony underneath — pick per agent.
02
Ground
Build a knowledge base from pasted text, an uploaded file, or a crawled website. One base attaches to many agents without duplication.
03
Dial
Place a real call to your own number from inside the builder. Flow agents can be test-called without even saving the configuration.
04
Review
Turn-by-turn transcript, duration and outcome for each call, plus a POST to your endpoint the moment the call ends so your systems stay authoritative.
Build
Two ways to build an agent
A linear question list when the call is a script, a drag-and-drop flow canvas when the call branches. Same voices, same knowledge, same telephony underneath — pick per agent.
- Classic builder: identity, engine, voice, opening and closing lines with {name} personalisation, and an ordered question list
- Flow builder: a node canvas with auto-layout, starter templates for lead qualification, appointment confirmation and feedback
- Full system prompt available when you need exact control of tone and rules
- Export any agent as JSON, review it in git, import it into another workspace
vox · configuration
- Agent name
- Renewals — Hindi
- Engine
- OpenAI Realtime + Cartesia
- Voice / language
- Aarav · Hindi
- Opening line
- Namaste {name}, calling from…
- Questions
- 4 in order
Ground
Answers from your documents, not the model's guesses
Build a knowledge base from pasted text, an uploaded file, or a crawled website. One base attaches to many agents without duplication.
- Three sources: pasted text, uploaded file, crawled website
- One knowledge base serves many agents — no copies to keep in sync
- Per-base indexing status is visible while it builds
- Swap the content and every attached agent picks it up on its next call
vox · configuration
- Knowledge base
- Policy handbook v4
- Sources
- 1 file · 1 crawled site
- Indexing
- Complete
- Attached agents
- 3
Dial
Test on your own phone before anyone else hears it
Place a real call to your own number from inside the builder. Flow agents can be test-called without even saving the configuration.
- Two dialers wired in: Smartflo and Twilio, selectable per call
- Test-call panel inside the builder, on real telephony
- Flow agents are test-callable before the config is saved
- Live dialer status while the call runs
vox · configuration
- Dialer
- Smartflo
- Test number
- your own phone
- Saved first?
- Not required for flows
- Status
- Live
Review
Every call comes back as a transcript and a webhook
Turn-by-turn transcript, duration and outcome for each call, plus a POST to your endpoint the moment the call ends so your systems stay authoritative.
- Full turn-by-turn transcript with duration and outcome
- Post-call webhook to your endpoint
- Per-session lookup by session id
- Retention stays with your systems, via the webhook
vox · configuration
- Turns
- 18
- Duration
- 02:14
- Outcome
- Renewal confirmed
- Webhook
- POST · 200
Two ways to build
A question list when the call is a script. A canvas when it branches.
Most phone calls are a fixed sequence, and a linear builder is faster to write and easier to reason about. When the conversation genuinely forks, drag it out as a flow instead. Both produce the same kind of agent.
Flow builderStrict mode
Drag nodes to branch the call. Auto-layout keeps it readable.
Flow agents run in one of two modes
The trade-off is real and worth choosing deliberately.
Flexible
Conversational calls where order barely mattersThe whole flow goes into the model's prompt and the model decides where to go next. No added latency, but it can take steps out of order.
Strict
Compliance and script-critical callsThe server tracks the current node and only shows the model the questions it has reached. One extra evaluation per reply, so slightly slower.
Specifications
What Vox does today
Only what's in the product right now — no roadmap items dressed up as features.
- Languages
- 10
- Voices
- 10
- Engine choices
- 2
- Telephony dialers
- 2
- Knowledge sources
- 3
- Post-call webhooks
- Yes
- Agent export / import
- JSON
- Workspace isolation
- Token auth
Languages & voices
- English
- Hindi
- Marathi
- Tamil
- Telugu
- Spanish
- French
- German
- Portuguese
- Arabic
Engines
- OpenAI Realtime + Cartesia
- Gemini Live
Telephony
- Smartflo
- Twilio
Where teams point it
Built for the calls a phone team makes all day
Financial services
Collections follow-up and verification calls.
Logistics
Delivery windows and reattempt coordination.
Retail
Order confirmation and status calls.
Customer support
Tier-1 self-service on the phone.
Not on the list? See the full range of voice use cases our team has built.
FAQ
Questions we get about Vox
Do we need engineers to build an agent?
No. An operations manager configures the agent in the browser — voice, language, opening line, the questions it must cover — and attaches a knowledge base built from your own documents. Engineers get involved for the webhook into your systems, and for the full system prompt if you want exact control of tone and rules.
Can we hear it before it talks to a customer?
Yes, and you should. There is a test-call panel inside the builder that rings your own phone on real telephony. Flow agents can be test-called before the configuration is even saved, so you can iterate on the wording without committing anything.
Which languages does Vox speak?
Ten today, each with its own voice, selectable per agent: English, Hindi, Marathi, Tamil, Telugu, Spanish, French, German, Portuguese and Arabic.
Does it work with our phone numbers?
Vox dials through Smartflo or Twilio, selectable per call. If you are on a different provider today, that is a conversation to have with us — the agency team handles telephony integration as part of a deployment.
Where do the call records live?
Each completed call returns a turn-by-turn transcript with duration and outcome, and posts a webhook to your endpoint the moment it ends. That keeps your systems authoritative rather than making Vox the system of record.
How do we get access?
Vox does not have self-serve signup yet. Access is granted per workspace, so book a call and we will set you up and walk through your first agent with you.
Want to hear Vox on your own phone?
Book twenty minutes. We’ll set up a workspace, build an agent for one of your real call flows, and ring your number with it before you decide anything.