1)   Outlook LAN Messenger 5.0.0
Instant messaging software designed for use within Small and Corporate Office's Local Area Network. Features include Text & Group Chat, Voice Chat, File Transfer, Offline Messaging. Its Server-less, requires No internet connection & Easy to install.

 2)   CapeSoft Office Messenger 3.00
CapeSoft Office Messenger is a peer to peer office instant Messaging program. It's great for sending all sorts of messages instantly to your office colleagues and it's easy enough for everyone to use. A must for every office.