To customize Skype sounds:
To add your own sounds, click Import Sounds and locate your own sound file.
Note: Skype does not support stereo WAV files for custom sounds and ringtones. Please use mono WAV-s files if you are adding your own sounds.
To restore your sound options to their default settings, click Reset to default.
If you don’t want sounds to play for any event in Skype, click Mute all sounds.