How To: Avoid Losing Your Unlimited Data Plan When Upgrading to the iPhone 5

The iPhone 5 will be here in no time. Pre-orders started at 12:01AM PST this morning and it's expected to start shipping in about two weeks. Verizon, AT&T, and Sprint are all handling unlimited data plans differently, so if you currently have an unlimited plan and are going to get the iPhone 5, you'll want to know what your carrier is doing before you upgrade so you don't end up with a very unpleasant surprise on your next phone bill.

Verizon

Of the three major carriers, Verizon's way of handling unlimited data plans on the iPhone 5 is the worst for consumers. As soon as you sign a new contract, your unlimited plan goes right out the window. The only way to keep it is to buy your phone at full retail value rather than getting the discount for signing the contract.

If you don't use a lot of data on your phone, it's probably not worth paying more for a new one. But if you use a lot more than 5GB per month, it could save you money in the long run.

AT&T

If you already have an unlimited data plan through AT&T, you'll be grandfathered in when you upgrade, which is awesome because AT&T discontinued unlimited data right before the iPhone 4 came out in 2010.

Just keep in mind that "unlimited" is a bit of a loaded word here—after the first 5GB, AT&T throttles the data. You're also stuck with the basic unlimited plan if you want to keep it. Adding anything extra to your plan voids the unlimited status and forces you into a tiered plan, including using FaceTime over Cellular. It's still a great deal if you use a lot of data, though, because overage charges are outrageous.

Sprint

If you use Sprint, you don't have to worry about paying full price for your phone or sticking with the plan you already have—you'll be able to sign up for an unlimited plan with the iPhone 5 even if you don't already have one.

If you use Verizon or AT&T, it's probably best to buy your phone in-store to be sure you don't lose your unlimited plan. Buying online is risky because there's no one to ask before you do it, and there are all sorts of little things that can cause you to accidentally do something that voids it. One little seemingly innocent change to your plan could mean the end of your grandfathered status.

Are you getting the iPhone 5? Do you think it's worth paying more to keep an unlimited plan?