How can I get data-only service for my old iPhone?

Wouldn't it be great if you could get a data-only service for your smartphone?

Wireless operators are pushing their new data services in a big way. They want everyone and their brother to upgrade to smartphones. And the reason is simple. Carriers can make more money if customers add more services to bills. But what if you just want data service?

In this edition of Ask Maggie I explain the best and cheapest options for using data only on a smartphone. I also answer some more questions about Verizon Wireless' plan to get rid of its unlimited data service for customers upgrading to its 4G LTE service.

How can I get a data-only service?
Hi Maggie,
I currently have an iPhone 4 and am looking forward to upgrading to the iPhone 5 this fall. I am concerned with the rumors that it will be a different form factor and will have a new dock connector as that will render accessories such as my automobile GPS windshield mount unusable.

I may have to keep my iPhone 4 to use as a GPS until new accessories for the iPhone 5 are released.

My question is would AT&T allow me to keep just a data plan on the old phone so that the GPS remains accurate and to keep the GPS traffic information available?

Thank you,
Bill

Dear Bill,
AT&T doesn't allow users to buy a cellular data service without signing up for a voice package as well. The least expensive voice service is $40 a month for 450 minutes.

But there are a couple of ways you can get data service for your old iPhone without breaking the bank.

Here are a couple of suggestions. First you could save about $20 a month if you sign up for an AT&T family plan. All you'd need to do is create a family plan and add your new device to the plan. For $60 a month you will be able to share a voice service with 550 minutes of talk time. Since a separate individual voice plan would cost you $40, you save $20 by combining voice plans and just using the old phone for data.

Keep in mind that until AT&T offers a family data plan, you will have to pay a separate data fee to get access to the AT&T 3G wireless network.

Another option for you is to add Wi-Fi hot-spot functionality to your new iPhone 5. For $45 a month, you can get up to 4GB of data to share between your phone and other Wi-Fi-enabled devices. If you disable the cellular network on your old iPhone 4 it becomes a Wi-Fi only device.

So you can use the Wi-Fi connection to get access to AT&T's network via your new iPhone 5. If the iPhone 5 supports 4G LTE, as is expected, this means that your old iPhone 4 will be able to download data at true 4G speeds.

Now there are some downsides to this approach. First, it requires that you have your iPhone 5 with you when you want to use data on your iPhone 4 (unless you can find other Wi-Fi Internet connectivity.) But since you're likely to have your iPhone 5 with you anyway, maybe it won't be a big deal to you.

Of course, you could also buy a prepaid Mi-Fi device that will essentially do the same thing as the personal hot spot feature on the new iPhone 5. But depending on the carrier you select, you may find it's worthwhile to have a separate device and service for your Wi-Fi connected devices.

Another option is to get a SIM card for an iPad 4G LTE. Verizon recently confirmed when an LTE SIM card is moved between devices, be it a smartphone to a tablet or Mi-Fi, the data plan tied to that SIM follows along. CNET blogger Jason Cipriani suggests popping out this SIM card and then popping it into your iPhone to get data-only service. Of course, this requires you to get your hands on an iPad SIM card. If you don't have an iPad, this could be a challenge.

I hope this advice was helpful. And good luck!

How can I hold onto my Verizon unlimited data plan?

Dear Luke,
Verizon hasn't yet disclosed what its policy will be regarding upgrades to 4G and the unlimited data plan. But based on what the company has done in the past, here's what I think will happen.

When your wife upgrades to a 4G device in December, she will have the option to get a new device for a subsidized price. If she chooses the subsidized phone, she will have to give up the unlimited data plan. But this should not affect your unlimited data plan, since the two of you are under separate contracts. You share a data plan, but you each entered into separate contracts when you signed up for the subsidy. Verizon can't change the terms of your contract in the middle of the contract. If it tried to do so, this is likely a significant enough change that you could cancel your service.

When your contract eventually expires, you will be faced with the same decision as your wife. If you want to get a new smartphone for a subsidized price, you'll likely have to give up your unlimited data plan.

As I mentioned above, Verizon hasn't officially announced the change in its pricing policy. The company is expected to announce a family share data plan, which could save you and your family money depending on how much data you actually use. Until we know more details, it's hard to say what the true effect will be. So stay tuned for updates. When Verizon announces its new plans and policies, I'll be covering it!

Should I buy a full-priced iPhone to keep my unlimited data plan on Verizon?

Dear Joel,
I've got some good news for you. The answer is yes. Verizon Wireless hasn't officially explained details of its new policy, but a spokeswoman clarified in an e-mail to me that if you keep your existing phone or buy your new device at full retail price when you renew your contract, you can keep the same old terms of your contract. In fact, this has always been true. Verizon and other wireless carriers generally let you keep your existing plan so long as you don't change it or sign a new contract with a subsidized device.

But given how expensive a new iPhone is likely to be at full retail price, I'm not sure it's really worth it. An unlocked iPhone 4S 16GB is $650. If you get it subsidized by a carrier it's only $200. If you don't use more than 2GB of data per month, which most consumers don't, then it's probably not worth the extra $450.

I hope this advice was helpful. And good luck!

Ask Maggie is an advice column that answers readers' wireless and broadband questions. The column now appears twice a week on CNET offering readers a double dosage of Ask Maggie's advice. If you have a question, I'd love to hear from you. Please send me an e-mail at maggie dot reardon at cbs dot com. And please put "Ask Maggie" in the subject header. You can also follow me on Facebook on my Ask Maggie page.