Connect to 3G only when Wifi is unavailable

[jmt356]

I am trying to conserve my paid-data use and to rely on free Wifi whenever it is available. Is it possible to set up my iPhone such that whenever my home or work Wifi networks is available, it will rely on that network and whenever I am outside of the home or office, it will connect to data via my carrier’s 3G network?

 

[J. A.]

As far as I know it'll choose whatever works better. To make sure you use either the one or the other, disable the service you don't want to use in Settings (either Wi-Fi, or Cellular).

 

[scifan57]

I am trying to conserve my paid-data use and to rely on free Wifi whenever it is available. Is it possible to set up my iPhone such that whenever my home or work Wifi networks is available, it will rely on that network and whenever I am outside of the home or office, it will connect to data via my carrier’s 3G network?

The normal preference is for your device to use WiFi, but to be absolutely sure you don't use cellular data when WiFi is available, turn off cellular data as J. A. Recommended.