VL Studio / AI / Voice agent developer
Voice AI developer · Vapi, Retell, ElevenLabs
Production voice agents on Vapi, Retell or ElevenLabs
You built a voice agent and it sounds off, talks over callers, loops or can't book. We design, build, test and maintain voice agents that hold up on real phone calls — on the platform that fits your use case, in an account you own.
New builds and rescues of existing agents · Last updated October 2026
Why DIY agents fail
A great demo is easy. A great call is hard.
Every platform gets you a talking agent in an afternoon. What separates a demo from something you can put on your main line is everything that happens when a real caller doesn't follow the script.
Awkward pauses
Slow models, long prompts, chained tool calls and far-away regions add up to silences callers fill with “hello?” Response time needs a budget, not hope.
Talking over people
Interruption and end-of-turn settings that work in a quiet room fail on a job site or in a car. Barge-in, backchannels and noise need tuning per use case.
Tool calls that break
Function calls with loose schemas, no timeouts and no fallback line. When the CRM is slow, the agent should say so gracefully — not loop or invent a confirmation.
Booking edge cases
Time zones, “next Tuesday,” buffers, double bookings, reschedules and cancellations. Booking is where most DIY agents quietly lose the caller.
Consent & AI disclosure
Call-recording consent and AI-disclosure expectations vary by state and country. The greeting, recording settings and data retention have to be set deliberately.
Nobody watches it
Prompts change, models update, a teammate edits the flow. Without regression tests and call review, quality drops and no one notices until a customer complains.
How we build
Scoped, built, then tested like software.
We treat a voice agent as a product: written call flows, explicit tool contracts, a test matrix that runs before every change, and monitoring after launch.
Call-flow design
We map your real calls — intents, questions, handoffs, emergencies — and agree on what the agent does, what it never does, and when it transfers to a human.
Build & integrate
Prompt, voice, tools and phone number on the chosen platform, connected to your calendar, CRM or field-service software with typed schemas and fallbacks.
Run the test matrix
Scripted and adversarial test calls across the scenarios below, with transcripts and recordings reviewed against pass criteria before go-live.
Launch & maintain
Staged rollout, call review, alerts on failed tool calls, and the same test matrix re-run whenever the prompt, model or platform changes.
Call test matrix
What we test before your customers do.
A shortened version of the matrix every agent passes before launch. Your build gets scenarios specific to your business on top.
| Scenario | What we check | Pass looks like |
|---|---|---|
| Happy-path booking | Slot lookup, confirmation read-back, calendar and CRM write | Correct slot booked, details confirmed aloud, record created |
| Interruptions | Caller cuts in mid-sentence, changes their mind, talks fast | Agent stops, listens and follows the new request |
| Noise & accents | Background noise, speakerphone, non-native speakers, spelled names | Key details captured correctly or politely re-asked |
| Dates & times | “Tomorrow after lunch,” time zones, holidays, fully booked days | Resolves to a real slot or offers alternatives |
| Tool failure | Calendar or CRM timeout, API error, empty results | Honest fallback: takes a message or transfers, never fakes a booking |
| Off-script & abuse | Unrelated questions, prompt-injection attempts, pricing it shouldn't quote | Stays in scope, follows your rules, no made-up answers |
| Urgent & human handoff | Emergencies, angry callers, “let me talk to a person” | Transfers or escalates per your rules, with context passed on |
Platform choice
Vapi, Retell or ElevenLabs? It depends on the job.
All three can run a solid phone agent. They differ in how much they let you configure, how they bill, and where they shine. We're platform-neutral and build in your account, so you're never locked in with us.
| Option | Vapi | Retell AI | ElevenLabs Agents | How we decide |
|---|---|---|---|---|
| Style | Developer-first, API-driven, highly configurable | Phone-call focused, with a visual flow builder | Built around ElevenLabs' own voices and speech stack | Your team's needs after launch: who edits it, how often |
| Billing model | Per-minute platform fee, with speech, model and telephony providers billed on top | Per-minute rate that varies with the voice, model and options you choose | Per-minute agent rate, with LLM usage billed on top and your phone provider billing you directly | Modeled on your expected call minutes before you commit |
| Shines at | Custom stacks, bring-your-own providers, complex tool logic | Fast, reliable receptionist and outbound call flows | Natural-sounding voices and multilingual conversations | Voice quality vs control vs speed to launch |
| Watch out for | More moving parts to configure and monitor | Less low-level control than a fully custom stack | Telephony and LLM setup are separate decisions | We handle the trade-offs and document them |
General characteristics as of October 2026, based on each platform's public documentation and pricing pages. Rates change often; we quote current all-in per-minute costs for your use case before building. We're not affiliated with any of these platforms.
Price
from $1,500 + $497/mo
AI Receptionist · New customers: $1,200 + $398/mo for the first 3 months
Custom voice agents — outbound, multi-step tools, multiple languages or complex integrations — start from $6,000 (new customers $4,800). Platform, phone and model usage are third-party costs, quoted up front.
Talk about my agent →- Call-flow design and written agent spec
- Build on Vapi, Retell or ElevenLabs, in your account
- Calendar, CRM and phone-system integrations
- Call test matrix with recordings before launch
- AI disclosure and recording settings configured
- Monitoring, call review and fixes on the monthly plan
Already built something that doesn't quite work? Send us the agent config and a few call recordings — rescuing an existing agent is often faster than starting over.
FAQ
Questions,
answered.
Can you fix the Vapi or Retell agent I already built?
Yes. We review the prompt, tools and call logs, run it through our test matrix and tell you what to fix — or fix it for you. Often the issue is latency settings, turn-taking or a fragile tool call rather than the whole design.
Which platform should I use?
It depends on who will edit the agent, how much custom logic it needs, and how much voice quality matters for your callers. We recommend one after scoping and explain why; we have no commercial reason to prefer any of them.
Who owns the agent and the accounts?
You do. We build in accounts registered to your business, so you keep the agent, phone numbers and data if you ever stop working with us.
What does it cost per minute to run?
All three platforms bill by usage, and the all-in rate depends on the voice, model and telephony you choose. We estimate it from your call volume before building, so you know the running cost in advance.
Will callers know they're talking to AI?
We recommend the agent say so in its greeting, and in some places disclosure is expected or required. We configure disclosure and call-recording settings with you; this isn't legal advice.
Can it book into my calendar or CRM?
Yes — Google Calendar, Outlook, Calendly-style tools, popular CRMs and field-service software, plus anything with an API. Each integration gets explicit error handling and a human fallback.
Next step
Tell us what it should do.
We'll make it hold up.
Thanks — your request was sent. We'll reply within one business day.
Please add your name and a valid email, then send again.