Scalable Social Calling App -- 2

I want to take the real-time friendliness of FRND or Dostt and package it into a polished, global-scale product that launches simultaneously on iOS and Android. The core experience must feel light and instantaneous no matter where the user is, so rock-solid architecture is as important to me as the interface users actually touch.

Key functionality
• Real-time 1-to-1 audio and video calls built on a low-latency stack (WebRTC, Agora, Twilio or a comparable SDK).
• Native push/in-app notifications that remain reliable even under heavy traffic.
• A clean, modern UI/UX that meets current App Store and Google Play guidelines and looks identical across screen sizes and device classes.

Behind the scenes I expect carrier-grade voice/video quality, end-to-end encryption, session hand-off on network change, and analytics hooks so we can watch usage at scale. Please factor in user authentication, user profile handling and a production-ready cloud deployment—AWS, GCP or similar—capable of horizontal autoscaling.

Deliverables will include
1. Source code for both platforms plus any shared libraries.
2. A deployed, load-tested backend with CI/CD pipeline.
3. Design files and clickable prototypes for final UI/UX.
4. Documentation and hand-over session so my internal team can maintain and extend the product.

When responding, highlight prior apps that pushed real-time media to tens (or hundreds) of thousands of users, the call SDK you prefer, and your approach to meeting App Store/Play submission requirements in one go.