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)   BigAnt Messenger 2.43
BigAnt Messenger is a secure corporate instant messaging program, with instant messaging, file sharing, voip, video chat, offline messaging, web conferencing, and group broadcast.