Here is a funny but effective way to check whether your Skype is well set and working. It is the official Skype echo test service, which consists of an automated user called echo123.
Send a sample of your voice, at most 10 seconds long, to echo123. It records it and plays it back to you! If you hear the echo, it means everything in your setup is working fine.
Another way is to send a text message which contains only the word callme to that user. In response, you will be called in order to start a sound check! Thus, you can check whether your Skype works both ways.
I know you must be asking, Wheres the Kerli you mentioned in the title? Well, according to some blogs, the voice you hear when using the echo123 service belongs to a young Estonian woman named Kerli.