The Virtual Office is Apache OpenMeetings
Apache OpenMeetings = The .net Virtual Office

Applications / Collaboration / Groupware / Communication

OpenMeetings is a web conferencing solution: useful for business or for education and training.

Features

Here is a non-exhaustive list of its features:

Video / Audio;
Desktop sharing with all participants;
Multi-language (19 languages ​​currently) and customizable;
Whiteboard with the possibility to draw, write and edit, resize, drag & drop, add image and symbol;
Import of documents (.tga, .xcf, .wpg, .txt, .ico, .ttf, .pcd, .pcds, .ps, .psd, .tiff, .bmp, .svg, .dpx, .exr,. jpg, .jpeg, .gif, .png, .ppt, .odp, .odt, .sxw, .wpd, .doc, .rtf, .txt, .ods, .sxc, .xls, .sxi, .pdf) ;
Sending invitations with a direct link to the conference;
Moderation system;
Moderation system by user / organization;
Backup module;
Language editing module;
Public and private chat.