24im is a group-based, private instant messaging service made exclusively for business use. You can create your own group for your office or create other private groups. Best of all, it’s free. So if you’re a business owner looking to save a buck (and who isn’t in this economy?), 24im serves as an option. Aside from IM, you also get project management tools, live chat support systems and file storage or sharing.

24im also uses Advanced Encryption Standard (AES) algorithms to protect sensitive information in your chat rooms.
 
24im provides chat rooms for internal users and allows external users entrance using a specific URL.

• Available as a desktop or Web-based application.
• Up to 1 GB of file and image storage.
• Instant broadcast messages to all or select members of a group.
• An administration application for creating users, workgroups and departments.
• E-mail forwarding of missed IMs.
• Built-in task management system.