According to Apple, "If an Application requires or will have access to the carrier network, then additionally such Application: ... May not have VoIP functionality." thus paving the way for Buzz Technologies mobile VoIP service to be used on all iPhones around the World.
www.12buzz.com has developed a line of Callback services which provides customers with three unique ways for making inexpensive calls around the world. No new equipment is needed; you use your existing telephone or mobile phone. It is as easy as using the web, sending an SMS message from your mobile phone or dialing a local access number to initiate a Callback call.
Buzz VoIP On the Move on Web This Callback method allows you to use a web application to initiate a Callback call. By simply accessing Buzz web application, two phone numbers can be connected at a predetermined time. By simply accessing any internet launch point at
www.12buzz.com/voip or end users panels to launch a call, the two phone numbers can be connected. You determine the two phone numbers you want to connect and specify the time for the call. Buzz will connect the two phone numbers at the predetermined time.
iPhone VoIP On the Move Similar to web callback, WAP callback can be initiated from any web enabled mobile phone. Simply go to any WAP enable web page from your mobile devices and initiate a web callback call at
www.mobi.12buzz.com.
You determine the two phone numbers you want to connect and specify the time for the call. Buzz will connect the two phone numbers at the predetermined time.
iPhone SMS On the Move Using only a mobile phone, this method allows you to call worldwide by simply sending an SMS or text message. You send a SMS message identifying the phone number you want to call. Buzz SMS On the Move calls back your customer and connects the call to the customer specified phone number.
iPhone ANI On the Move Buzz's ANI On the Move method allows you to use a local access number to initiate the call. You must first register your phone number using the Buzz VoIP control panel or by using one of our many publicly accessed VIN or DID. The Callback call is initiated by dialing a local access number from any registered phone. You receive a call back from Buzz and the call is connected to any phone number you specify.
The limitations on iPhone VoIP over cellular is probably a requirement from AT&T and is part of their contract. Buzz VoIP can be used on any phone, anywhere, anytime