Why you can't take your unlocked iPhone 4S to another U.S. carrier

If I can unlock my Verizon iPhone so I can use it on a local carrier’s network while I’m on vacation in Europe, why can’t I pop in a SIM card to that same unlocked phone, and use it on AT&T or T-Mobile when I get home?

In this edition of Ask Maggie, I explain why the term “unlocked” doesn’t really mean “unlocked” when it comes to the iPhone 4S.

Why a Verizon Wireless unlocked iPhone 4S won’t work on AT&T

Dear Maggie,

I have a Verizon Wireless iPhone 4S. But I think the service is too expensive. I’d like to get a prepaid SIM card and use it on AT&T or T-mobile. I unlocked my iPhone 4S a few months ago when I traveled to Europe. And I used a SIM card from a local carrier while I was there. But when I came home to see if I could get a prepaid SIM from AT&T or T-Mobile, I was told by sales associates at Verizon and AT&T that even though my iPhone 4S is unlocked, I can’t put a U.S. carrier’s SIM card in it. Is this true?

That doesn’t make sense to me! When I am abroad, my unlocked iPhone 4S will work on any other GSM carrier, so why won’t it work like that on a GSM carrier in the U.S.?

If I cancel my contract and pay the cancellation fee, I should be able to use my phone on other carriers. Please tell me I’m not stuck with Verizon for as long as I have this iPhone!

Thanks,

JD

Dear JD,

Here’s a short answer to your question. Unfortunately, the iPhone 4S that you bought from Verizon only works on Verizon’s network here in the U.S.

(Credit: Apple)

I completely agree with you that this makes absolutely no sense given the fact that hardware components in an iPhone 4S from Verizon are exactly the same as the components in an iPhone 4S from AT&T and the same as the unlocked iPhone 4S sold throughout much of the world.

This of course is different from most other device launches, where carriers build different devices for different markets and even different carriers, depending on whether they are a CDMA carrier, like Verizon and Sprint are in the U.S. or whether they’re a GSM carrier, like AT&T, T-Mobile, and most other operators in the world.

In theory, this should mean that a so-called “unlocked” iPhone 4S from any of the three major wireless carriers in the U.S. or the unlocked version available from Apple should work on any GSM network and any CDMA network. (Remember it has components that can handle both types of networks.)

But the reality is that the iPhone 4S is never really “unlocked.” The carriers, which sell these phones directly to subscribers, require that the devices remain locked to their networks. This means that it’s very difficult, if not nearly impossible, to use an iPhone 4S from Verizon on any other carrier’s network in the U.S. And iPhones sold for other carrier networks in the U.S. will not operate on Verizon’s network.

The Verizon and Sprint versions of the iPhone 4S are programmed to predominantly operate on CDMA networks. They can be “unlocked” for international use, which means that certain SIM cards can put in them to get access to foreign carrier’s network. But if you try putting in a SIM card from AT&T or T-Mobile to an unlocked Verizon or Sprint iPhone 4S, you’ll get an error message.

Marc Weber Tobias, a contributor to Forbes, wrote back in December that he tried this with a Verizon iPhone he purchased at full price from Best Buy, but was meant for the Verizon network. He explained how he had to jump through a series of hoops just to get his device unlocked from Verizon. He used his unlocked iPhone 4S just fine in Europe, but when he tried to insert a prepaid SIM card from a carrier that uses AT&T and T-Mobile’s network, he got a message saying he was using an unauthorized SIM. But then he popped in his European carrier SIM card and his phone connected via the foreign carrier to AT&T’s network.

 

Why you can't take your unlocked iPhone 4S to another U.S. carrier