Native AI Customer Support App

I need a fully native mobile application that can answer incoming phone calls on our main business number, speak to the caller in either a male or female voice, and resolve their questions from a built-in knowledge base—no external APIs allowed at any stage... (Budget: ₹1500 - ₹12500 INR, Jobs: .NET, Android, Flutter, Machine Learning (ML), Mobile App Development, Python, React Native, SQLite)