Android Chat App Development - repost

Required to develop Android based real time chat application for phone and tablet, including backend. App features: - user authentication - user registration will be handled via back end (manual registration) - user profile with pictures - user wall (like Facebook) - user search - user friend and group invite, with option to accept and reject - user photo gallery - adding of friend via QR code scanning - listing of friends - viewing of others profile and pictures - commenting on friend's wall - user groups / social circle - group page with picture - text based real time messaging (like whatsapp) with emoticons, picture attachment, stickers and audio clip attachment - real time voice conference room with multiple users, able to reject user, turn based (requires request to speak from initiator) - 1 to 1 video conference like FaceTime - supports localisation in Chinese language Backend features: - back end to utilise open source as much as possible - to support deployment on cloud services e.g. AWS, Azure and Appfog - audio and video preferably to use SIP, but please feel free to recommend alternative (MUST be proven to support China users) - administrative user authentication and management (for administration only) - app user manual registration by administrators - app user management by administrators - to include installation package Important Note: candidates to propose back end that can support operation in China