no persistent Wi-Fi since iOS 4.3
*In iOS 4.2.1* to have push notifications over Wi-Fi instead of the carrier you can leave the iphone connected to a power source or just disable mobile data and 3G. The second way you will miss MMS but are still connected to Wi-Fi persistent even if the iPhone is in sleep mode (Display locked). According to Apple, the carrier is priorized over wi-fi for push notification.
*In iOS 4.3* there is no way to have Wi-Fi persistent. It drops the connection after about 20 seconds - with a wireless-consuming app after 5 minutes the latest. The only chance to stay wireless is to connect to a power cord (that in most cases is a wire). So persistent wireless is not available anymore.
With iOS 4.3 you therefore have to use your cell carrier for push notifications an the according mail transfers even if you are within your organization with WPA2-Enterprise and Exchange Environment. This is slower, less secure and lets not forget to say unnecessary expensive.
We just informed Apple by feedback form. How is your Experience? Can you confirm this behavior or has someone a solution for it?
Thanks
punktlandig
iPhone 4 black 16GB, iOS 4, iOS 4.3 and iOS 4.2.1