Vista SysTech Limited
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SaaS

Responzic AI

A white-label SaaS for deploying AI voice agents that answer calls 24/7, book appointments, and capture leads — with multi-tenant admin and usage-based billing.

Vista SysTech product 6 min read

24/7

AI call answering

Next.jsVoice AIStripe

The Problem

Every missed call is a missed customer. Small and mid-sized businesses — clinics, trades, salons, agencies — can't staff the phones 24/7, and traditional call centres and IVR menus are expensive and frustrating. At the same time, the underlying voice-AI technology (Vapi, ElevenLabs, Twilio, Stripe) is powerful but fragmented: wiring it into a billable, multi-tenant, compliant product is a serious engineering effort that most businesses and agencies can't take on themselves.

Responzic AI closes that gap. It packages best-in-class voice-AI infrastructure into a single platform where a business can stand up a working AI phone agent in minutes, and where an agency or operator can resell that capability to many clients under one roof — with metering, billing, and administration handled for them.

What Responzic Does

Responzic lets a business create an AI voice agent, give it a phone number, and put it to work answering calls. The agent greets callers, follows a configured prompt and business hours, holds a natural conversation, books appointments, captures lead details, sends SMS, and hands structured data back to the business — then logs a recording, transcript, AI summary, and sentiment for every call. Above the individual business sits a super-admin console that runs the whole platform: tenants, phone numbers, voice assistants, packages, billing, coupons, referrals, and reports.


Capabilities

Voice Agents

  • Create and configure agents: system prompt, first message, voice, language, model, temperature, max call duration, silence timeout, and business hours
  • Dual voice providers — Vapi and ElevenLabs — selectable per agent
  • AI Agent Builder — a conversational, Anthropic-powered assistant that builds and edits agents for you, with token/cost tracking and a daily cost ceiling
  • Reusable agent template library (including ready-made medical templates)
  • Function calling so agents can take actions mid-conversation (look up availability, book, capture data)

Telephony & Messaging

  • Connect Twilio, provision and assign phone numbers, label them, enable SMS, and release them
  • Inbound and outbound calling
  • Outbound campaign engine — upload CSV contacts, control concurrency and pacing, track per-contact status, and capture AI follow-up notes
  • SMS logging and Twilio Messaging Services (sender pools); WhatsApp messaging in the medical module
  • Twilio regulatory bundles & business-address provisioning for compliant number setup

Call Intelligence

  • Automatic recording, transcript, AI summary, sentiment, cost, and outcome for every call
  • Structured data capture per call, with post-call email notifications (via Resend) delivering the transcript, summary, and collected fields to the business
  • Analytics dashboards over calls, usage, and outcomes

Multi-Tenancy, Teams & White-Label

  • Full multi-tenant model — every agent, number, call, and subscription is tenant-scoped
  • Role-based access (Owner / Admin / Member / Viewer) with permission middleware and team invitations
  • Per-tenant white-label branding (logo, colours, custom-domain field) and per-tenant encrypted provider credentials
  • Agent and messaging-service assignment history for transferring resources between tenants

Billing & Monetization

  • Stripe-powered subscriptions with embedded payments and multiple saved payment methods
  • Usage metering for minutes and SMS, per-agent daily usage, and quota enforcement (max agents, numbers, included minutes/SMS)
  • Agent-level billing — each agent can carry its own subscription
  • Add-on purchases (extra minutes/SMS), coupons, referrals, billing adjustments (credit/debit/refund), grace periods, and an auto-renewal scheduler
  • Configurable subscription packages with per-minute and per-SMS overage rates

Super-Admin Platform Console

A comprehensive operator console spanning ~15 modules: users, tenants, packages, billing, phone numbers, messaging services, voice assistants (with an AI-chat configurator), call logs, SMS logs, analytics, referrals, reports with scheduled CSV/Excel/PDF/JSON exports, coupons, and an audit log — so the platform can be run and resold at scale.

Security & Compliance (implemented)

  • AES-256-GCM encryption for all stored provider secrets, with secret masking
  • Audit logging (actor, IP, before/after state) across the platform and a dedicated medical audit trail
  • Tenant isolation, RBAC, Stripe raw-body signature verification, and svix-verified webhooks
  • Consent capture in the medical vertical (consent timestamp/method/call, opt-in flags, configurable data-retention)

Featured Vertical: MediCall AI — Medical Appointment Booking (Australia)

Responzic ships with a fully implemented healthcare vertical for the Australian market — 24/7 AI phone booking for GP and specialist clinics. It's a complete backend module and dashboard, not a demo:

  • Booking requests, doctors, availability rules, and patient records
  • Appointment scheduling with urgency detection, 24-hour and 2-hour reminders, and ICS calendar invites
  • Inbound SMS and WhatsApp handling, patient notifications, and medical-specific prompt templates
  • A medical analytics dashboard, practice settings, and consent/retention controls aligned to Australian healthcare privacy expectations (Privacy Act / APP, AHPRA)

This vertical demonstrates the platform's core thesis: the same voice-agent engine, specialized into a high-value, compliance-aware product for a specific industry.


Built With

LayerTechnology
FrontendNext.js 14 (App Router), React 18, TypeScript, Tailwind CSS, Shadcn/ui, React Query, Zustand
BackendNode.js, Fastify 4, Prisma ORM, TypeScript (ESM), Zod validation, Pino logging
DatabasePostgreSQL (Neon)
AuthClerk (with svix webhook user-sync)
Voice AIVapi and ElevenLabs (per-tenant, per-agent)
TelephonyTwilio (voice, SMS, WhatsApp, Messaging Services, regulatory bundles)
PaymentsStripe (subscriptions, embedded payments, coupons, refunds, metering)
AI (agent builder)Anthropic
EmailResend
Monorepo & toolingpnpm workspaces, Turbo, Docker
HostingVercel (web) + Railway (API)

Architecture: a two-app monorepo — a Next.js dashboard and a Fastify REST API — communicating over a webhook-driven event flow. Vapi/ElevenLabs call events, Stripe billing events, and Clerk auth events all arrive as webhooks, are deduplicated through an idempotency layer, and update call, usage, and subscription records. A built-in billing scheduler handles auto-renewals and provider sync.

Integrations

IntegrationRole
VapiPrimary voice-AI provider — assistant creation, calls, phone-number import, webhooks
ElevenLabsSecond voice provider — agents, conversations, data collection, webhooks
TwilioNumbers, SMS, WhatsApp, Messaging Services, regulatory/compliance provisioning
StripeSubscriptions, payments, add-ons, coupons, refunds (signature-verified webhooks)
ClerkAuthentication and user identity
AnthropicConversational AI Agent Builder
ResendTransactional and post-call notification email
Neon / PostgreSQLPrimary data store

Business Model

Responzic monetizes through tiered subscription plans with included call minutes and SMS, per-minute and per-SMS overage, and add-ons — enforced by configurable packages and quota limits in the platform. Billing can operate at the tenant or individual-agent level, and coupons and referrals support growth. The model is designed for three audiences: businesses buying 24/7 phone coverage, agencies reselling under their own brand (white-label), and vertical operators (like the medical vertical) delivering a specialized product.

Outcomes & Highlights

  • A complete, resellable voice-AI SaaS — not a wrapper around one API, but a multi-tenant platform with billing, metering, white-labeling, and a full operator console
  • Best-of-breed voice engines, abstracted — Vapi and ElevenLabs behind one consistent agent model, with Twilio telephony and Stripe billing fully wired
  • A productized vertical — the Australian medical-booking module shows the platform delivering real, compliance-aware business value, not just generic call handling
  • Operator-grade administration — ~330+ API endpoints and ~58 dashboard pages spanning tenant self-service and platform super-admin
  • Security built in — encrypted credentials, audit trails, RBAC, and consent capture from the ground up

Roadmap

The following are designed and partially scaffolded, targeted for upcoming phases:

  • Make.com / Zapier automation and generic CRM connectors for no-code integration
  • Google Calendar / external calendar two-way sync (the medical module currently issues ICS invites)
  • HotDoc and medical PMS integrations as the headline differentiator for the healthcare vertical
  • Enterprise super-admin hardening — granular admin RBAC, MFA, session management, monitoring/alerting, and support tooling
  • Knowledge-base uploads and in-browser test calls

Designed, built, and owned by Vista SysTech — full product architecture, backend, dashboard, integrations, and platform operations.