iCall is an intelligent iPhone application that lets users switch between VoIP and normal GSM calls anywhere in North America - effectively using the WiFi at Starbucks to make a call. We're told this is an official Apple-approved application that's expected to debut at the App Store soon.
Features include:
Make and receive calls over WiFi
Transfer inbound calls from a regular cell call to WiFi instantly and seamlessly - save your expensive minutes
Access your same address book
Customize your voicemail options