Except WiFi probably won't work without a plan, so there's really no point.
WHy wouldn't WIFI work without a plan?
I have WIFI on my phone and can use it anywhere there is a open access point. How I use my WiFi functionality is none of FIDO's business, and neither can they do anything about it, even if they wanted to ( apart from cancelling my monthly contract ).
No cell phone provider should imped the WiFi functionality of the phone ( aside from disabling it ).
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For those hoping for VOIP, Apple may choose not to expose the API in the SDKs....
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Finally, if you think 3rd party software will make your iPhone unstable, dont install any

But don't restrict 3rd party software.