Collanos Phone is three tools in one - a multi-protocol instant messaging client, VoIP app and a video conference suite.
The program supports a multitude of IM clients and protocols including Jabber, MSN, ICQ, AOL, and Yahoo! The VoIP phone function is based on the Session Initiation Protocol (SIP) standard while the Instant Messenger is based on the popular Extensible Messaging and Presence Protocol (XMPP) standard. As far as conference calls are concerned, it doesn't support more than three callers at a time which is a definite drawback for large meetings. It is very well organised though in the way it shows useful information about contacts in the profiles. The program is based on existing Collanos user profiles so if you use any other Collanos products, the profile is instantly imported and shared in Collanos Phone. The other thing that makes life easier is that you make calls from the Windows taskbar - simply right click on the Collanos Phone symbol and you are given options to call or start conference calls.
A very basic but professional VoIP and IM client that's suitable for businesses although general users won't find all the fun features you find in most similar communication suites such as MSN Live Messenger.