Go to www.teamspeak.com and follow instructions according to the pictures below :

In addition, after you've used TeamSpeak, come download this Voice Overlay program.
This application will enable you to see who log in to channel, who is talking etc

Click Here to Download (If got advertisement, just click on the mediafire link below)

To use it, follow these steps (With images)
1) Extract it to a folder that you like. In this case i extract it to D:\Games\Voice Overlay
Double Click on VoiceOverlay.exe to launch the program. Don't launch Rappelz first.




You should be able to see the following screen once you launch Voice Overlay
2) Ensure Teamspeak is active and running. Don't Run Rappelz first.




Click on the Options Button to open the Voice Overlay Options:



3) Now that Teamspeak2 is connected, Voice Overlay is active,
proceed to launch Rappelz. You should now have a transparent little menu that will
show you who is talking, who left the voice channel, who join voice channel etc.



I hope this guide helps
Happy Rappelzing