Experienced Full-Stack Team Needed: Production-Ready AI Voice Agent SaaS Platform (Multi-Tenant, Multi-Provider, Long-Term Partner) Job Description We are a new venture building a multi-tenant AI Voice Agent SaaS platform that enables organizations to automate outbound and inbound calling campaigns across multiple industries. Initial focus areas include debt collection, customer support, and appointment booking, with a clear roadmap to support additional verticals over time. We have a detailed Functional Requirements Document ready to share with shortlisted candidates. This is not an MVP build. We want a production-ready, market-grade platform from day one, built to scale, built to support enterprise clients, and built to expand into new industries without major rework. The Core Concept Think of this as a configurable AI calling engine. Clients upload their contacts, configure their AI agent's behavior and parameters, launch campaigns, and the platform handles everything from there. The platform is multi-tenant, meaning each client organization operates within a fully isolated workspace. The platform is designed to be industry-agnostic, with configurable templates, outcome classifications, and compliance parameters that can be extended as new verticals are onboarded. Key Technical Requirements Multi-Provider Architecture This is the most critical architectural requirement. Rather than being locked to a single provider, the platform needs to support a modular, swappable provider layer across three areas: Voice and TTS generation (ElevenLabs, Cartesia, Azure Speech, Hume, LMNT, and others) LLM and model providers (OpenAI, Anthropic, Google, Mistral, Azure OpenAI, and others, including custom endpoints) Speech-to-text and transcription (Deepgram, AssemblyAI, Azure Speech, Gladia, and others) Tenant admins need to be able to select their preferred providers per use case, and the system needs to make it straightforward to add new providers over time. We want candidates who have thought through how to build this cleanly using abstraction layers, provider adapters, and fallback logic. Telephony SIP Trunk support is mandatory, as clients need to be able to bring their own accounts Twilio integration is preferred as a managed option We are open to other managed providers if the team has strong reasons to recommend them The telephony layer should follow the same modular approach as the provider architecture above Platform Modules The full scope covers the following modules, details of which are available in the FRD shared at screening stage: Authentication and user management with role-based access control Multi-tenant contact management with CRM sync capabilities Outbound and inbound campaign engine with multi-step workflow support AI agent strategy builder with configurable conversation and negotiation parameters SMS and email template management Analytics, reporting, and usage monitoring Outcome classification engine Payment and telephony integrations RAG knowledge base management at both tenant and system level Superadmin panel for tenant management, usage controls, and monitoring What "Production-Ready" Means to Us A clean, documented, and maintainable codebase Proper test coverage on core business logic A security-first approach where multi-tenant data isolation is non-negotiable Scalable, containerized infrastructure built to handle growing client volume A CI/CD pipeline with automated deployments from day one Monitoring and alerting with visibility into system health and errors in production Tech Stack We are open to the team's recommendations. What matters to us is that the stack suits the scale and complexity of the system, that the team is genuinely expert in what they propose, that the architecture supports the multi-provider modular design, and that we retain full code ownership. Ideal Team Profile We are looking for a team or agency, not a solo freelancer: Proven experience building multi-tenant SaaS platforms at production scale Hands-on experience with VoIP and telephony integrations, with Twilio strongly preferred and SIP experience required Experience integrating LLM APIs and building AI-powered conversational products Familiarity with real-time audio pipelines covering STT, LLM, and TTS in low-latency voice flows A strong portfolio demonstrating complex backend systems with workflow and campaign engines A clear project management process with regular client communication Capacity and genuine interest in a long-term engagement Bonus points for: Prior work in debt collection, contact center, or outbound dialer software Knowledge of TCPA and FDCPA compliance requirements Experience with RAG and vector database implementations Familiarity with platforms like Vapi, Retell AI, or similar AI voice agent frameworks Long-Term Partnership and Revenue Opportunity We want to be transparent about what this relationship can grow into. The initial engagement is to deliver the full production platform as scoped in the FRD. From there, we expect an opportunity for ongoing post-launch support, performance improvements, and incremental feature development. As clients onboard, many will need integrations with their existing CRM systems, additional payment processors, and new industry vertical configurations. The right team can take these on as direct revenue opportunities, either channeled through us or negotiated directly with the client. Longer term, the platform roadmap includes new provider integrations, advanced analytics, white-label capabilities, and additional industry verticals. We see this as a multi-year technical partnership, and the right team gets a serious, well-scoped project with real long-term upside. What We Need in Your Proposal Proposals without the following will not be reviewed: Two or three relevant past projects covering SaaS platforms, VoIP/telephony, or AI-powered voice applications, with links or descriptions Your recommended tech stack with a brief rationale, especially how you would approach the multi-provider architecture A timeline estimate for a full production build A budget range for the full scope Your team structure, including who works on this and in what roles Your project management approach covering milestones, communication cadence, and QA process One paragraph on why your team is specifically the right fit for this project We will share the full details under NDA and answer technical questions in a screening call with shortlisted candidates. Budget We are open to competitive, honest pricing from teams that can genuinely deliver. We have prior estimates as a benchmark and prefer milestone-based billing. We are not looking for the lowest bid. We are looking for the best value from a team we can trust long-term.