ATT sim card with country unlocked foreign Iphone

Contributor

ATT sim card with country unlocked foreign Iphone

[ Edited ]

Hi,

 

I frequently travel to S. Korea.   In U.S. I am currently using blackberry under ATT data plan.   Also, I have an Iphone 4 which was purchased in Korea and is being used in Korea.  The korea service provider unlocked the country code for the Iphone. 

 

Can I use my iphone (that was purchased from Korea) in U.S. if I just plug ATT sim card into Iphone that is used in my blackberry?   Is the monthly charge for data plan and voice with the Iphone same with blackberry?

 

Because I have used the blackberry for more than two years, I do not have any contract restriction.

 

I just want to use one equipment in both Korea and U.S.

 

Thank you.

 

 

Message 1 of 8 (3,722 Views)
Guru

Re: ATT sim card with country unlocked foreign Iphone

AT&T uses 850 and/or 1900mhz bands. If the Korean iPhone uses one or bothe of those bands, it should work. You probably won't get 3G speed though. Ultimately, putting your sim in the phone would be the best test. It will either work, or not.
Message 2 of 8 (3,617 Views)

Re: ATT sim card with country unlocked foreign Iphone

If your South Korean mobile company and/or your iPhone 4 uses the same network frequencies as AT&T, then you should be able to purchase or receive an AT&T MicroSIM and place it into your iPhone 4...which should give you access to at-least AT&T's E network and all of their services...

Message 3 of 8 (3,610 Views)
Guru

Re: ATT sim card with country unlocked foreign Iphone

Ohhh that's right. I forgot about the micro sim issue. Makes it tuff to put you BB sim in the i4.
Message 4 of 8 (3,607 Views)
ACE - Master

Re: ATT sim card with country unlocked foreign Iphone

As others have mentioned, there is a possibility that the phone may use a different frequency than AT&T, but I believe that is a small chance.

 

The bigger issue is that even if you cut the sim down to fit, it won't all work right unless you contact AT&T.  Tis past summer, my wife moved her SIM from her Blackberry Bold into my old iPhone 3G.  The phone worked and could make/receive calls.  None of the data services worked right until she contacted AT&T to get some minor changes done to her account setup.  Also she had minor issues with voice mail that were corrected by the phone call to AT&T.

 

Her monthly bill did not change, since the Blackberry already had a grandfathered unlimited data plan, she kept that, and her minutes stayed the same (well technically, she voluntarily reduced that to lower her bill) and she is still "contract free" and happy.


Jerry B.
"GeekBoy"

--

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*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
Message 5 of 8 (3,578 Views)
Contributor

Re: ATT sim card with country unlocked foreign Iphone

Thank you for the reply..  I still have two questions. 

 

1. Could you explain more why not get 3G speed? The MicroSIM in US will store ATT data/calling plan..

 

2. In Korea, the provider use  UMTS/HSDPA 2100 Mhz.  However, is it matter because the Iphone can support 850, 1900, and 2100?  I meant, would the phone automatically pick up any available frequency that the phone supports?

 

Please bear with me... I am not the engineerer.

 

 

Message 6 of 8 (3,426 Views)
Contributor

Re: ATT sim card with country unlocked foreign Iphone

One additional question...

 

Someone told me me that I need to reset Iphone through Itune whenever I change the Sim card.  Is it right?? 

 

Pleae let me know..

Message 7 of 8 (3,399 Views)
Highlighted

Re: ATT sim card with country unlocked foreign Iphone

 


jhujb20 wrote:

One additional question...

 

Someone told me me that I need to reset Iphone through Itune whenever I change the Sim card.  Is it right?? 

 

Pleae let me know..


 

I do not believe that statement is true.

 

I have several unlocked AT&T iPhones and have changed sims without ever using iTunes.

 

What you "may" need to do is reset the APN code for the new carrier.

 

There is a web site out of New Zealand that will help you to reset your APN based on the carrier, free service.  I used him a few months ago when returning from another country and my AT&T sim had a problem with 3G data when I arrived at LAX.

 

google unlockit  New Zealand.   He doesn't talk about that dreaded unlock word,  but does explain the APN issue.

 

 

 

 

Message 8 of 8 (3,314 Views)
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