Using a tablet SIM to turn a smartphone into a data-only device

In this Ask Maggie, CNET's Marguerite Reardon advises a reader looking to use a SIM card from a tablet to get data-only wireless service on his smartphone.

Why do wireless carriers have to make everything so complicated? Wireless subscribers should be able to subscribe to the service they want and need and not be forced to take services they don't want or need.

This seems like a simple enough concept and yet customers who want a smartphone but only want to pay for voice services can't get it. And customers who want to forgo voice service for data-only services are also not able to get what they want. In this edition of Ask Maggie, I offer some advice and explanation to a reader on this topic.

Gaming the system

Dear Maggie,
I don't need a voice plan for my smartphone. I just want a data-only plan so that I could use Google Voice and Skype for any calls that I might need. But I'm confused. The wireless carriers I've talked to claim that you can't use atablet SIM card in your smartphone, so that you can get a data only plan.

But I've talked to some store representatives who say it can be done. And I've read online about people being able to this. I've also read other blogs and message boards where people say it can't be done, because the carrier needs the device IMEI number to register the it with the service etc.

My first question is what's the right answer here? And if carriers don't allow it, why not? Seriously, why can't I have just data on my Samsung Galaxy S3 or on the Galaxy Note 2? Something doesn't add up here.

Thanks,
Nemanja

Dear Nemanja,
In theory, you should be able to take a tablet SIM card and use that in a smartphone, so long as the SIM cards are the same size. (SIM cards now come in different sizes micro-SIM, nano-SIM etc.)

But another thing you need to make sure is that the network technologies and supported radio frequencies are compatible. For example, wireless subscribers on a GSM network, such as AT&T's or T-Mobile's, have always enjoyed the flexibility of a SIM card, which allows them to change service on a device simply by removing their SIM from one device and placing it in another.

By contrast, CDMA doesn't use SIM cards. So CDMA wireless customers on services, such as Verizon and Sprint, have had to call and request that their service be changed each time they get a new device. But as these carriers roll out LTE, this will no longer be the case. LTE also uses SIM cards, which means that service could be switched from one device to the next by popping out the card and putting it in another device.

What this means for you is that you should be able to pop out a SIM from a GSM carrier's tablet or an LTE tablet and use it in a smartphone.

As you point out in your question, the major carriers don't sell data-only SIM cards. So the data SIM you would use for your smartphone needs to come from an already activated tablet. Once the SIM has been activated, and the IMEI number on the device has been recorded by the carrier, you should be able to put it into a smartphone or even a Mi-Fi device.

Verizon Wireless has publicly acknowledged that this is possible, although the carrier doesn't promote the practice. The companytold the blog Phonenews.com in March that you could use your SIM on another device and the service from that SIM would then move to the new device.

The SIM holds the detail of your data plan. If you move it to another device, you will be charged for the service you use. If you have an unlimited SIM and it fits another device, you can use it and you will pay for the service plan associated with the SIM.

CNET blogger Jason Cipriani tried this in March. He used a SIM card from the third generation iPad on Verizon and put it in a Galaxy Nexus smartphone. And he said the Galaxy Nexus was able to get data service using the SIM card, but it could not get 4G LTE service.

Remember that Verizon doesn't offer a data-only service for smartphones. So this means that you will be using a service that's not really intended for a smartphone. And even though Verizon won't likely cut off your service or force you into a voice plan, it also won't provide customer service or support if your smartphone is having network issues.

While popping in a tablet SIM into a smartphone may work on Verizon's 4G LTE service, it may not work on other carrier services that also support SIM cards. For example, a T-Mobile representative told me that it provisions SIM cards for tablets and smartphones differently, so there is no guarantee that taking a SIM from a tablet will work in a smartphone, even if the devices take the same sized SIM card. There have also been some AT&T customers who have said they've been able to use their tablet SIMs in a smartphone and vice versa. But they say that AT&T was able to detect the device using the service wasn't the one registered to use that service. Once AT&T detects unusual usage, it asks customers to subscribe to the appropriate service.

So what does this mean for you? I've seen mixed stories of success on the Web about whether or not this will work. As I mentioned above, technically it may work. But then the carrier may find out what you're doing and still try to charge you for a certain level of service.

My advice to you is that I wouldn't go out and buy a tablet just to avert the voice service charge. For one the cost of a full priced tablet can be hefty. That said, if you happen to have a 3G tablet from a GSM carrier or a 4G LTE tablet from any of the four major carriers, you could try it and see if it works.

I agree with you that the major wireless operators should offer customers the services they want. And if that means selling someone a data-only service, that's what they should do. In fairness to the carriers, that's likely to be a small portion of their customer base. But still, it shouldn't be a big deal to offer someone data-only when these companies are perfectly capable of offering voice-only service to basic phone subscribers.

The truth is that carriers aren't eager to give up the voice revenue, because it's such easy money. It doesn't cost a carrier much money to offer voice and text messaging services. But the carrier can still charge a relatively high amount for these services, which helps boost its profits.

This is why you see AT&T and Verizon Wireless offering unlimited voice and text messaging with their new mobile share plans. They can offer unlimited voice and text messaging service because people are actually talking less. But also because it doesn't cost much to offer that service.

Meanwhile, it's very expensive to deliver data services. And because usage is increasing, carriers have to invest more in their networks to keep up with demand. The more they invest just to keep up, the more money they spend and the less profit they make.

Forcing customers to buy voice minutes is a way to boost revenue and lift profits.

But even though all four major wireless companies today require that customers buy voice service as part of their mobile packages, it might not always be that way. In fact, AT&T's CEO Randall Stephenson said in June while speaking at a conference that data-only plans would likely be offered within the next two years, according to published reports.

But even though the big carriers aren't offering data-only services, it doesn't mean that other companies aren't offering it. There is a small mobile virtual network operator or MVNO calledSimple Mobile, which offers a $25 data-only plan. The company uses T-Mobile's network. And all that's needed to start the service is an AT&T or T-Mobile GSM phone and a data-only SIM from Simple Mobile.

Even though T-Mobile doesn't offer a plan without any voice service, it does offer a prepaid plan with lots of data and not many voice minutes. T-Mobile's plan gives subscribers 5GB of data and only 100 minutes of voice for $30 a month. That's a pretty good deal considering all the data that's available.

I hope this advice and explanation were helpful. Good luck!

Using an AT&T iPhone on Verizon?

Dear Maggie,
I really like how your articles get at some of the root issues facing cell phone buyers these days! I was hoping for your input on an issue of my own. My friend recently bought the iPhone 5 and now has an iPhone 4S sitting in his desk drawer. He said that I could have it, if I could make it work. The only problem is that he has AT&T as a carriers and I am on Verizon Wireless. Do you know if AT&T has loosened up its phone locking requirements for older phones now that the iPhone 5 is out? Is there some way I could use this iPhone 4S on Verizon? He is not under contract with the iPhone 4S anymore and I know the iPhone 4S was made with both a CDMA and GSM radio inside.

Thanks,
MDtower

Dear MDtower,
I have some bad news for you. You will not be able to use the AT&T iPhone 4S on Verizon's network. I know it doesn't make much sense. You are correct that the hardware for these phones is exactly the same. But the CDMA radio on the AT&T version of the iPhone 4S is disabled. And since Verizon uses CDMA on its domestic network, it simply won't work. I'm afraid your only option if you want to use this phone is to switch carriers to AT&T. Sorry!

If you want to know more about this issue, please check out an Ask Maggie column I wrote back in August. It offers a more detailed description as to why this is the case.

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.