TeamTalk 

This program lets you make conference calls between you and several щерук persons at the same time. It lets you share text, audio, and video messages, as well as sharing desktop applications. Those features are very useful when the team members are in different locations, and even in different countries. Of course, each of them needs to have a copy of the program installed in their system.

The program is very easy to use. At startup, you can connect to one of the several free servers that the program offers. Then, you can create a channel to which you can invite your teammates. Once you have done that, all of you can start sharing text messages, as well as video (providing that you and the rest of the members have a webcam installed in your system), different types of files such as PDF, MS Office documents, sounds, graphics, and more. Also, if you and your teammates have microphones, you can voice-talk using the program. A nice feature is the possibility of sharing what you are doing on your desktop. This is especially useful when you are teaching training courses or instructing your team on how to use an application or follow a process.

If you are the channel manager, you will have the credentials to manage the participation of the rest of the team. For example, you can mute somebody's microphone, or kick and ban an annoying or uncollaborative participant. Another good feature is the possibility of recording conversations for future reference.

The best part of all this is that the program is free to download and use. The program's interface may be a little dull, but this does not affect the performance of the program. If you do a lot of online teamwork, then you may want to give this program a try.