Patient Messaging App Development

I need a fully-featured mobile app published on both Google Play and the App Store so my patients can reach me easily and securely. The core experience is a private messaging channel between each patient and myself, backed by phone-number authentication with a one-time password flow (no email or social log-ins).

Inside the chat screen patients should be able message and also start voice with a single tap. All conversations, calls, and bot interactions must remain HIPAA-compliant and encrypted in transit and at rest.

I am open to the tech stack—React Native, Flutter, or native Swift/Kotlin are all fine—as long as the final build passes App Store and Play Store review guidelines. You will also set up the lightweight backend necessary for OTP verification, real-time messaging, call signalling, and the chatbot logic, then hand off clean, well-commented code and the deployment documentation.

Deliverables:
1. Production-ready iOS & Android apps (source + store-ready builds)
2. Secure backend with OTP auth, chat, voice/video, and bot modules
3. Admin access for me to monitor chats and manage bot rules
4. Deployment notes, API keys, and a quick-start guide for future updates
5. Swipe Payment for Sessions

Once published, I should simply log in, verify everything works, and start chatting. Let me know your proposed approach, timeline, and any questions that will help you estimate the effort accurately.