Social Networking Chat App Development

I'm looking for an experienced developer to create a social networking chat app for iOS and Android platforms. The app should include:

- User Profiles: Customizable user profiles with photos, bios, and interests.
- Group Chats: Ability to create and manage group chats for various topics and interests.
- Voice and Video Calls: Integrated voice and video calling features.

Ideal Skills and Experience:
- Proficiency in mobile app development for both iOS and Android.
- Experience with real-time messaging and call functionalities.
- Strong UI/UX design skills to ensure an engaging user experience.
- Familiarity with backend services to support user profiles and group chat functionalities.

Please provide examples of similar work and estimated timelines.