A new iPhone is coming next month, and thanks to an increased number of carriers and the virtually guaranteed inclusion of LTE technology in the next-generation handset, you may be thinking of changing wireless carriers. Historically, pricing has been a key factor, but leading U.S. providers AT&T and Verizon have all but synchronized their pricing schemes at this point, as discussed in our How To Choose A New iPhone / iPad Shared Data Plan article. There are, however, major differences in LTE network coverage and speeds, as well as other factors, so pricing is not necessarily the single most important aspect when choosing a wireless provider.

We’re going to run down five key factors besides price that you should take into should take into consideration. Understanding the pros and cons different carriers offer will help you make the best decision for your personal needs.
1. LTE Coverage
Real-world cellular coverage has always been a major consideration when it comes to choosing one carrier over others: a phone’s no good if it stops working where you live, work, or frequently travel. Now that brand-new LTE networks are being added to the mix, cellular coverage is going to be even more important—and confusing—than before. Verizon was the first carrier to roll out an LTE network, and that lead time has given it a chance to grow the largest LTE network in the United States. As of this writing, Verizon LTE is available in 337 cities, and the company claims that it covers nearly 75% of the U.S. population.

AT&T’s 4G LTE network—not to be confused with its HSPA+ network, the cause of the recent “4G” symbol next to the bars on the AT&T iPhone 4S—is newer, but growing. Right now it’s live in 51 markets, and in AT&T’s words, LTE deployment should be mostly complete by the end of next year. One could assume that this means LTE will roll out to all of AT&T’s markets by the end of 2013, but it’s unclear whether that’s the company’s planned scope or not.

Sprint’s freshly launched LTE network has a tiny footprint. As of now, it’s only live in 15 markets, most of which are located in Georgia and Texas. So little LTE support exists for Sprint that there isn’t a LTE version of the already-released third-generation iPad being marketed to Sprint customers. We’d expect that this will change in the very near future.

2. LTE Speeds and Backwards Compatibility
As we saw in our tests of the third-generation iPad, the difference between connecting to LTE or 3G/4G can come down to the distance of just a few streets, and create order of magnitude speed distinctions. Consequently, it’s crucial to take a look at the coverage maps for your home and frequently traveled areas—if possible, ask a friend who already has an LTE device to visit your home or office, so you can see what coverage you’ll actually get in the places you live or work. LTE speeds with Verizon are great, for example, but if you end up dropping down to CDMA 3G in areas you frequent, you’ll see a slow down so significant—say, a 90% speed drop—that you may think your data connection is broken. Sprint users should expect similarly sharp chokes when their LTE devices fall back to the company’s old network.

By comparison, AT&T’s LTE network isn’t as big yet, but its 3G/4G data speeds are much faster. When an AT&T LTE device falls back to the company’s larger, older network, the speed penalty is similarly significant—potentially a 90% drop in some places—but AT&T’s lowest 3G/4G speeds are generally faster than Verizon’s and Sprint’s, so the fallback won’t feel as rough. Moreover, AT&T’s fastest LTE speeds have been higher than Verizon’s fastest in our tests. So if you’re in one of the fewer LTE markets covered by AT&T, it may be a better choice, while Verizon’s LTE coverage is broader but with bigger penalties for leaving LTE service.
3. FaceTime Over Cellular
When Steve Jobs announced FaceTime alongside the iPhone 4 in 2010, he said it would be a Wi-Fi-only feature in 2010, but Apple intended to “work a little bit with the cellular providers to get ready for the future.” WWDC 2012’s announcement of iOS 6 saw that future finally hit; starting this fall, FaceTime calls will be able to be placed and received over cellular networks. It’s unclear at this point whether carriers will charge extra for this feature, or allow it to simply count against users’ data allotments.

A pop-up menu seen in a beta release of iOS 6 suggests AT&T may be preparing to charge for FaceTime, although there’s been no official word, and other carriers seem to be open to treating video calling as regular data. Video quality may also be impacted by the LTE speeds and coverage in your area. Over time, users who have the freedom to make FaceTime calls at any location will likely increase the feature’s popularity. If you already find yourself frequently placing or receiving video calls, the ability to do so without extra fees may be important.
4. Shared Data Plans
We’ve explored AT&T and Verizon’s new shared data plans in detail, but here’s the gist of it: going forward, cellular companies hope to simplify their data plans with a two-step billing process, charging you solely for a pool of pre-paid monthly data and the number of phone/tablet/computer devices you want to share the pool. With this system, unlimited voice minutes and SMS/MMS messaging are included in the price, though you’ll pay more than you would have for limited voice minutes and messaging. AT&T will maintain its standard individual and family accounts as options once it introduces Mobile Share, but Verizon has made Share Everything the only option for new subscribers. If you have multiple devices or people sharing an account, these new plans are fairly reasonable, but they’ll be significantly more expensive for an individual user with a single iPhone. Sprint hasn’t announced any similar plans, and seems to be sticking to its traditional service offerings, though that can change.

5. Large vs. Small Carrier
Most iPhone owners in the United States are on traditional postpaid plans with major carriers. Over the past year, though, Apple has added 13 additional partners in addition to AT&T, Sprint, and Verizon. Some, such as Alaska Communications and Golden State Cellular, are limited to customers in specific geographic regions. Others such as Cricket and Virgin Mobile are national. Each has different service plans, and even iPhone hardware pricing; some require a multi-year contract and monthly fee, while others offer the ability to buy the handset at full retail price and then use the phone from month to month on a prepaid basis. This kind of plan can yield dividends for users who don’t want to be obligated to long-term contracts.

You’ll have to decide for yourself whether to spend the money up front to buy the phone outright, or to make a smaller up front payment with mandatory monthly charges running for two years thereafter. Bear in mind, however, that Apple may not supply smaller carriers with the next iPhone on day one, and that it has traditionally waited to sell full-priced unlocked phones until it was done fulfilling initial orders for its contract-dependent carrier partners. We’ll have to see whether this changes going forward, but it’s possible that early U.S. adopters of the next iPhone will need to sign up with larger carriers to get the device quickly.
If any or all of the factors above has helped you decide to change carriers, do a little more research on your own personal situation before jumping ship. If you choose to leave your current carrier before your contract is up, you’ll have to pay an early termination fee. This calculator will help you figure out what it’ll be, but check with your provider to get the exact figure. There’s also a possibility that not-yet-announced features of the new iPhone could benefit from certain carriers as well, so while you can start your decision process now, hold off on a final decision until the dust has settled. Carriers may provide additional “stick with us” incentives that haven’t yet been announced, and if they do, you might find yourself staying “loyal” for another couple of years.