Voxa is an AI receptionist SaaS I designed and built end-to-end, on my own, to solve a problem every service business faces: missed calls mean missed revenue. It answers phone calls and WhatsApp messages 24/7, automatically books, reschedules, or cancels appointments, captures leads, and handles customer questions all through natural conversation, with no scripted menus. The system is multi-tenant, so each business can configure its own hours, services, and pricing. At its core is a tool-calling AI agent shared across both voice and WhatsApp channels, built with safeguards so the AI can never double-book a customer even if a request is retried, and a human-escalation path for anything it can't confidently resolve on its own. I built the real-time voice pipeline myself speech-to-text, AI-driven conversation handling, and text-to-speech and evaluated several telephony infrastructure options to keep the system cost-efficient and self-hostable rather than dependent on expensive third-party voice AI platforms.