What You Must Know before Buying a Verizon iPhone 4

Following the long-anticipated official announcement of the iPhone 4 on Verizon, it's certain that folks who have been longing for an iPhone and loathe AT&T will be among the first to reserve one beginning Feb. 3.

Before anyone takes the leap, however, it's important to understand the differences between the iPhones and their service plans. And you'll want to be aware of fees you could incur by switching providers.

Verizon vs. AT&T

Carriers bank on the clout of signature phones like the iPhone, which until now was only available through AT&T. The Verizon iPhone was built to be compatible with Verizon's CDMA network as opposed to the AT&T iPhone that runs on the more widely used GSM network. Bottom line: You can't take an AT&T iPhone over to Verizon or vice versa.

CDMA technology currently does not allow voice and data to be sent over the network simultaneously, which means you can't, for example, make a phone call while checking e-mail or using the maps app, but you can with a GSM AT&T iPhone.

Also, the  ringer/mute button had to be slightly moved, which means the bumpers and cases available for the iPhone 4 (GSM) may not fit.

Verizon did not claim exclusivity for the CDMA iPhone 4 at its launch event today (Jan. 11), which seems to leave the door open for a Sprint version, since Sprint also uses CDMA.

As for the phones themselves, the Verizon iPhone can be used as a mobile hot spot so that multiple devices can share its Internet connection; the AT&T iPhone does not have this capability. Verizon's version can share a Net connection via Wi-Fi with up to five nearby devices, such as an iPad or laptop, for no additional fee.

Verizon will be expected to offer its unlimited data plan with the iPhone, but declined to offer details or pricing. AT&T retired its unlimited plan prior to the iPhone 4 release last June. AT&T now offers two options for the iPhone: $15 a month for 200-megabytes of data or $25 for 2GB of data. iPhone users must purchase one of the two plans.

However, Verizon’s iPhone will still download data at 3G speeds, not the faster 4G , or LTE, speeds which will become available this year on other Verizon handsets.

How to avoid early termination fees

If you do plan to switch to Verizon from AT&T or another carrier, you’ll most likely have to pay a hefty termination fee to get out of your contract. For AT&T, the termination fee can be as much as $325.

Early termination fees were designed to cover the provider's costs in subsidizing phones. Most carriers charge about one-third of the full price of a smartphone to customers who sign up for a new two-year contract or are eligible for an upgrade . Instead of paying the full price up front, you are spreading the balance over a period of the contract.

If you're intent on switching providers before your contract expires, you can transfer the contract to a friend or relative. You and your friend will need to go into the store together to make the switch. Alternately, online companies such as CellSwapper.com and CellTradeUSA.com can help with the process, but you will pay a fee of between $15 and $20.

iPhone 5

Another thing to remember if you’re contemplating switching is that the iPhone 5 will most likely launch in June. It is rumored the new version will offer 3G-enabled Face Time and an improved processor.

Keep in mind, if you sign a contract with Verizon in February for an iPhone 4, you will not be able to upgrade to an iPhone 5 until Sept. 2012 — and by that time the iPhone 6 will be available.

• 5 Reasons to Buy the Verizon iPhone, and 5 Reasons to Not
• Verizon Cuts Upgrade, Return and Warranty Policies
• How to Put Your Data Hungry iPhone on a Diet