Low-Latency Video Conferencing App

I need a video conferencing app that supports iOS, Android, and Web platforms. The app should support up to 10 participants and include the following basic features:
- Chat functionality
- User authentication
- File sharing

The app's standout feature should be live annotation, allowing users to draw over the live screen share.

Ideal skills and experience:
- Expertise in real-time communication (RTC) technologies
- Experience in developing cross-platform mobile and web applications
- Familiarity with low-latency video streaming
- Strong background in UI/UX design for seamless user experience
- Proficient in implementing secure user authentication systems

Please provide a portfolio showcasing similar projects.

Price is just placeholder.

Feel free to offer