This is a major change from Apple's previous agreement with AT&T which only allowed VoIP communications over a Wi-Fi connection. In a press release issued late yesterday, iCall broke the news and claimed to be first and only VoIP application available for the iPhone platform that allows use over 3G networks -- at least for now. With the restriction lifted, we expect Skype, Truphone and other similar calling apps to get on board soon.
Currently, iPhone voice plans from AT&T start at $39.99 and go up to $199, while unlimited data will set you back an additional $30. In theory, this means you could cut your bill to around $80 a month by sticking to the cheapest voice plan and using iCall's $9.95 Total Access plan for unlimited local calls and cheaper long distance. The possibility of free Skype-to-Skype calling over 3G sounds really tempting as well.