No there is no impact on customers that already have unlimited data. The reps have been instructed to tell you that you can't move the unlimited data feature between lines. For example if your ordered the upgrade on a line that had no data plan, a vaild data plan had to be selected for that line when you pre-ordered from Apple or AT&T. If you ordered the upgrade on a line that already has unlimited data and you want to do the upgrade swap of the iPhone 5 from that line to another line, you can't move the unlimited data plan but you can move the device.
If the rep knows their job, they will not need to touch the donor line that you orderd the iPhone 5 as an upgrade.
What you all want to do is to be very carefull that you make sure that the rep understands that you don't want a new data plan on any line that already has an unlimited iPhone data plan unless it is the new LTE iPhone plan, it this is the name to verify: Data Unlimited for iPhone on 4G LTE. This is like the name change for the 4S but the LTE plan will allow you to use 5GB before any throttling is applied.
Dave
Thank you for the plan name, Dave.
My concern was more that some rep would be confused, not that AT&T would be trying to deliberately steal my data plan.
It's good to have the name though. Take some new, confused reps and put them on the phone all day long with packed phone lines and you really do have to know exactly what you're asking for.
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What about those of us who didn't preorder? I'm standing in line tomorrow, and using my wife's upgrade. AT&T rep told me tonight that I don't need to take her phone, and in fact, I can just tell them I want to use her eligibility and upgrade my line, and there's no need for a SIM swap. Should I assume I need to buy my 5 at an AT&T store, and not an Apple store?
I do not think it will matter as long as you are the account holder.
You might have an ordeal if your wife was the account holder and she wasn't present.