# Smartphone unlock question
**URL:** https://boards.straightdope.com/t/smartphone-unlock-question/690041
**Category:** Factual Questions
**Created:** [June 4, 2014, 4:52pm UTC](https://boards.straightdope.com/t/smartphone-unlock-question/690041 "2014-06-04T16:52:35Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@Xema](https://boards.straightdope.com/u/Xema)
#### Post date: [June 4, 2014, 4:52pm UTC](https://boards.straightdope.com/t/smartphone-unlock-question/690041/1 "2014-06-04T16:52:35Z")
I have an old Samsung AT&T phone that I hope to take with me on a trip overseas. Research says it’s compatible with the phone system where I’ll be. It will certainly need a SIM card that allows service there.
It’s currently locked to AT&T, and will need to be unlocked. I’ve obtained an unlock code from AT&T - directions are: Insert new SIM card, and turn phone on. When the message “Your phone is currently locked - enter unlock code:” appears, enter the 8-digit code and all will be right.
My notion is that I should complete this unlock step before I depart - I’m not sure if some sort of contact with an AT&T network will be necessary for this to work. My first question: Is this correct?
Assuming it is, I’ll need to obtain a non-AT&T SIM card to complete the unlock process. Suppose I just borrow one for a moment from some cooperative non-AT&T friend? Will that work, or is there a chance that when he puts the SIM card back in his phone, problems ensue?
Your expertise will be much appreciated.
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### Author:  [@smiling\_bandit](https://boards.straightdope.com/u/smiling_bandit)
#### Post date: [June 4, 2014, 5:11pm UTC](https://boards.straightdope.com/t/smartphone-unlock-question/690041/2 "2014-06-04T17:11:04Z")
I’m not 100% certain of AT&T’s current policies, but they will probably unlock it for you gratis if you visit a store. otherwise, you can pick up a prepaid sim in an airport (presumably when you leave) and use that.
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### Author:  [@Terry\_Kennedy](https://boards.straightdope.com/u/Terry_Kennedy)
#### Post date: [June 5, 2014, 7:38am UTC](https://boards.straightdope.com/t/smartphone-unlock-question/690041/3 "2014-06-05T07:38:43Z")
> [@Xema](#):
>
> It’s currently locked to AT&T, and will need to be unlocked. I’ve obtained an unlock code from AT&T - directions are: Insert new SIM card, and turn phone on. When the message “Your phone is currently locked - enter unlock code:” appears, enter the 8-digit code and all will be right.
That’s the plan. When the phone detects a non-AT&T SIM, it will ask you for the subsidy unlock code. There’s no communication with the AT&T network during this process.
> [@](#):
>
> My notion is that I should complete this unlock step before I depart - I’m not sure if some sort of contact with an AT&T network will be necessary for this to work. My first question: Is this correct?
The reason to do it before leaving is to be able to easily reach AT&T customer service in the event of a problem. Getting to 800 numbers from overseas can be problematic at best, you’ll be paying for the call, etc.
> [@](#):
>
> Assuming it is, I’ll need to obtain a non-AT&T SIM card to complete the unlock process. Suppose I just borrow one for a moment from some cooperative non-AT&T friend? Will that work, or is there a chance that when he puts the SIM card back in his phone, problems ensue?
It should just work. Note that if you do a master reset/clear on your phone while the other person’s SIM is installed, it may clear any phonebook entries stored on the SIM (phones can store to local memory, SIM, or both).
I keep a bunch of random SIMs of different form factors around so people can verify their unlocked status. The first 3 I pulled out just now are mobi4U (Vietnam), Maroc Telecom (Morocco), and some random prepaid one from Portugal.
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### Author:  [@Digital\_is\_the\_new\_Analog](https://boards.straightdope.com/u/Digital_is_the_new_Analog)
#### Post date: [June 6, 2014, 2:29am UTC](https://boards.straightdope.com/t/smartphone-unlock-question/690041/4 "2014-06-06T02:29:46Z")
The only thing I’ve seen go wrong with the “insert another person’s SIM card” is if you are putting it in a something that needs a special data plan, and their carrier decides they should be paying extra. I did that to myself coming back from Costa Rica - I had my personal SIM card in my wallet, but was carrying a spare Blackberry as a throw-away phone in case of trouble. When I landed in Miami, I put my personal SIM in the BB to check voice mail. AT&T noticed and added a BB data plan to my account…which they removed after I complained.
But fundamentally…yeah You can just put someone else’s SIM card from another carrier in to trigger the SIM unlock message, and it’s a good idea to do so before you go on your trip.