As expected, the VOIP app requires a WiFi connection to make and receive calls; it will also handle conference calling - albeit limited. The 1st version doesn't have SMS capability, call waiting, the integrated voicemail tool.
Skype text chat, unlike voice traffic, will work over an EDGE or 3G connection.
I already use Fring - that can talk to the Skype voice network. On a jailbroken iPhone you can use Skype over the 3G connection.
Know that when calling another Skype user (to a Skype line on a computer) that typical phone call laws DO NOT APPLY.
BUT, if you are calling from Skype to a land line or cellphone the law governing the person you are calling applies.
Please check out my comprehensive reference on RECORDING TELEPHONE CONVERSATIONS [below]