Collax Groupware Suite is a complete collaboration, e-mail, and messaging server with Outlook MAPI support. It offers enterprise email server functions, anti-spam and anti-virus filters, GUI management, a file server for SMB, NFS, FTP, and Apple shares, backup/restore server, IM server, and fax and SMS server. The groupware offers AJAX Web mail, calendar, team calendar, contacts, and tasks, and supports ActiveSync for mobile devices. It is free for private or commercial use of up to five users.
The Taridium ipbx is a complete software-based VoIP PBX system that replaces a traditional proprietary hardware PBX. It runs on Linux without the need for extra software licenses, and is based on the SIP standard. It supports many phones and is available for free in a 5 user version.