I've got the grandfathered AT&T unlimited plan in my iPad Mini. I'm thinking about experimenting with purchasing the unlocked T-Mobile iPhone6+ and swapping in this iPad SIM. According to various web pages, this should work in the iPhone to provide data-only service: http://misener.org/ditched-voice-plan-went-data/ https://discussions.apple.com/thread/5579806 However, I'm a bit vague how this would work and what risks there might be. Would the iPhone "just work" with this data or would I need to enter the IMEI for the phone into att.com/ipadlanding? Would the IMEI for an iPhone be accepted on that page? Would my data plan be messed up if I later wanted to switch the SIM back into the iPad? Alternatively, I might consider the AT&T mobile share plans described at: http://www.att.com/shop/wireless/data-plans.html#fbid=EcegNbhpn5J The $50/mo plan for 1GB might work for me, and I could share it with the iPad mini for $10/mo (if I dropped its unlimited plan). Even better would be the data-only mobile share plans described on that same webpage, which start at $30/mo for 4GB! The webpage vetoes use on smartphones, but I wonder whether it could be used on iPads if activated at an AT&T store or over the phone. Ideally it'd be great to share 4GB data for $40/mo between an iPad and a data-only iPhone6+. BTW, T-Mobile's plans would be an option if they ever get LTE in my area instead of 2G speeds.