Computer software requirement

Conference Video Call System

A company need to create a local conference video call system to facilitate the communication between its employees across the world. The requirements are:

·  The admin shall be able to add new users to the system.

·  The admin shall be able to remove users from the system.

·  The user shall have a contact-list containing other users.

·  The user shall be able to add other users to his contact list.

·  The user shall be able to schedule a conference video call.

·  The user shall be able to invite other users from his contact list to his conference video call. 

·  The user shall be able to accept/reject a conference video call 

·  The user shall be able to join conference video call that they were invited to.

·  The user shall be able to send chat messages in the conference video call chat.

·  The system shall notify the user when an accepted conference video call time is close.

·  The system shall notify the user when another user accepts/rejects their invite.

Assignment1: Design a block diagram for the system.

Assignment2: Design a Database schema for the system. 

Note: assume any missing requirement

Please write it as doc and make it simple design. 

This is not coding assignment , just thinking written in design.