How to enhance Skype calls?

[aimo3]

I have a fast internet connection and I use Skype to phone and Skype to Skype. The voice quality is generally OK, but it's annoying when it breaks and lags sometimes. I heard that in some smart phone VOIP apps there are some codecs that you buy for enhancing the quality of voice calls. I am not sure about that, but I am wondering if there is a way whether free or paid that improves Skype calls as well.