KC5AV wrote:I read somewhere that folks in the past have had trouble keeping their grandfathered unlimited data plan when they upgrade through the website, so I'll just wait a few extra days.
Speaking as a former Apple Senior Advisor, if this does happen (which has always been EXTREMELY rare (and usually has a singular cause which I'll explain in a minute), a simple call to Apple can get it resolved. When you get ahold of the Apple Advisor, just explain the situation to them and ask for a Senior Advisor. The SA can then get you in touch with AT&T's Product Management Center (PMC) who can resolve the issue. Please note that you cannot get to PMC by calling AT&T directly. AT&T's General Care advisors do not have access to PMC and can rarely help you in situations like this.
As for what usually causes these issues, it's usually because a has 2+ lines on their account and their phone isn't eligible for upgrade but one of the others is. So they upgrade line 2, and then try to activate the new phone on line 1 instead of the line it was ordered under (line 2). This causes no end of trouble. If you are ordering your phone on one line in order to use it with a different number, please, PLEASE, complete the activation on the line it was originally ordered under. Then go into an AT&T store (corporate, not reseller) and have them do a SIM swap. It takes all of 15 minutes and will save you multitudes of trouble.