There are 2, count them two...two..not one...skype apps in the market.
One app allows 3g, the other app allows wifi. There are two (2), not one, apps to download. Download both apps and use them interchangeably.
You have to download two different apps. Not one app. Search skype in the market. One app is called "Skype"...the other one is called "Skype for Verizon"...install BOTH