How to Unlock SIM on AT&T/T-Mobile/Canadian Galaxy S4! [SGH-i337/SGH-M919/SGH-i337M]

For those of you who want to unlock SIM on your AT&T or T-Mobile Galaxy S4, there’s an easy way to unlock SIM as outlined by XDA user kaleido.

This should work on AT&T Galaxy S4 SGH-i337, T-Mobile Galaxy S4 SGH-M919, and also all Canadian SGH-i337M variants.

Remember, unlocking SIM is illegal in the U.S. as of this year, and that is why I cannot make a video tutorial but this method does work well, you can find full step-by-step tutorial at XDA here.  However, it is not illegal to unlock your SIM if you are currently in another country other than the U.S.  This law should change soon as it only benefits carriers not consumers.

The process involves getting into Service Mode on your Galaxy S4 by typing “*#27663368378#” on your dialer and messing with some of the settings similar to the “Note 2 SIM Unlock method.”

To test the your Galaxy S4 has been fully unlocked, you need to insert another carrier SIM on your phone.  E.g. If you are using AT&T S4, you can insert a T-Mobile SIM card to test this out.

As a bonus note though, if you are a current customer of AT&T, they will just give you your unlock code if you ask for it and also same goes for T-Mobile. In case they don’t give you unlock code, you can use this method.

Why would you want to unlock SIM?

When you unlock SIM on your Galaxy S4, you are not locked down to AT&T or T-Mobile, you can use your phone worldwide on any network that supports SIM cards.  E.g. You can turn your AT&T Galaxy S4 into a full-fledged T-Mobile S4 by unlocking your SIM then applying the AWS band MOD.

What is a Custom ROM?

A custom ROM is a custom, modified operating system that you can install on your Android device. Basically it's like installing Windows OS on a Macbook. By installing a custom ROM, you can bypass stock factory settings like locked hotspot tether, install new Android versions early, or even convert your phone into another OS.

With a custom ROM, you can really maximize the capabilities of your smartphone by adding custom features that have been developed by open source developers.

How to Install Custom ROMs

First, you will need to root your device, if it is not rooted yet, follow our root tutorial and root your phone.

Once rooted, you should have TWRP installed on your phone. Installation of a custom ROM is easy if you learn the basic of it. If you don't know how to install custom ROMs using TWRP recovery, see our tutorial on How to Install Custom ROM using TWRP!

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44 Responses

  1. Dave says:

    I will be traveling back and forth to Japan and possibly Spain later this year. I want to be able to swap out SIM cards while abroad to avoid huge fees and bills. What model would I best be served with? I’m looking to root and unlock. I’m thinking of going with Verizon model, but could easily be swayed to AT&T. Please help!

    • Yuki says:

      If you are coming to Japan buy the tmobile version. It supports softbank and docomo lte and their 3G network. Also tmobile galaxy s4 supports extra LTE bands you can maybe use them in other countries. Sadly galaxy s4s in North America don’t suppor one of the 3g bands used in Spain but if you get orange it shouldn’t be a problem

      • Yuki says:

        One more thing if you are ok with just 3G you can get a Verizon version or an AT&T version as long as you know how to unlock sim.

        • Do you have any more information on making the galaxy s4 and s4 active work here in Japan? I’m trying to get mine to work and I’m almost there, but I can’t call, I wonder if I missed a step or something. If you could help me I would really appreciate it. Thank you.

    • Diane Scott says:

      If you’re with AT&T, Sprint, T-mobile and other huge phone networks, they can usually provide the code needed to unlock your phone, irregardless of the model 🙂 I’m not entirely sure if you will need to pay them (probably – but hopefully not! It can also take time). In case you’re not quite ready to do this though, you can try I used it before for my phone and I didn’t have any problems.

  2. ms.samsprung says:

    Hi Max,
    Sorry if this isn’t the appropriate location or if I’ve missed it somewhere else but, could you give us a little more of a detailed explanation of what’s going on with the Sprint S4 and its being a CDMA phone with a SIM card slot & coming with a SIM card in place. I’ve been able to find little bits of info here & there and can kinda connect the dots but would like to know whether my conclusions are accurate or not.
    Thanks as always for everything you do for us newbs (not to be confused w/ noobs), ms.samsprung.

    • Max Lee says:

      I am not that sure either… but you should be able to flash .qcn file with gsm bands NV files with qpst.

  3. xsudis says:

    Get your AT&T iPhone, Galaxy, Lumia 820, 920, and HTC factory unlocked for as low as $10. Super simple!

  4. zaryan says:

    Can someone confirm if its working on M919V
    i337M Canadian Versions?

  5. Bruno says:

    Do you know if is there any compatible ROMs for GT-I9508 (S4 Chinese version)? I’d appreciate your help.

  6. StellarVice says:

    Works in Mexico. Tried it for unlock to IUSACELL. The Message pops up as Unauthorized SIM but eventually goes away after rebooting a few times..

  7. James says:

    Does this procedure work well for T Mobile Galaxy S4 ?

  8. fred says:

    Is there a sim unlock guide for the sprint varient of this phone?

  9. Pappu says:

    Tried. Followed the steps precisely. it rebooted after restoring from backup but I still get the SIM lock screen when I use a SIM from another network..

  10. Brenton says:

    Hi, I used your other tutorial on how to flash the 9505 rom onto the i337. I also did your tutorial on how to get the LTE working using the qualcomm application and such. Here’s the question I have though, when I boot the phone up and insert an at&t sim, it says wrong sim but works…and then when I insert a T-mobile sim in, it asks for the unlock code. I’ve gotten the code from AT&T but when I type it in it doesn’t work…is it because I flashed the 9505 ROM to it and it doesn’t know how to handle the code? If I flash it back to stock and then use the unlock code and then wipe it and install the 9505 rom would that work?

    Thanks so much for your help btw…

    • Max Lee says:

      No, shouldn’t matter, if it works for one SIM it should work for the other. Not sure what’s going on here but do you have another AT&T SIM you can test with?

      • Brenton says:

        I’ve tried with 2 different AT&T SIMs and 1 T-mobile SIM. It asks for the unlock code and refuses it every time with the T-mobile SIM but seems to work OK with the AT&T SIMs. I’m sort of at a loss… it just doesn’t make sense to me why none of the unlock tutorials or even entering the code from AT&T works. It’s not giving me a ‘freeze’ message or anything indicating that I’m locked out by entering the wrong code too many times…

        Unless you have any thoughts I think I’m going to just wipe it, install stock i337 and try to unlock it with that, then wipe and install 9505 and see if that works.

        Once again thanks for your help…

  11. wirelessG says:

    Hey, thanks for posting this. I have a Verizon S4, and am about to head to Indonesia for a while, where I’ll try to pop in a local SIM card, probably Telkomsel. I’ve read various comments by folks who claim they’ve done this without any APN adjustment or even rooting (although mine’s rooted already), they just switch the antenna setting to ‘global’. Do you know if I will need to set up a whole APN profile manually (as in your Note 2 video) to get data there?

    • Max Lee says:

      Hmmm it may work let me test it later this week.

      • wirelessG says:

        Well, I’m heading out today, so I’ll post my results here when I get them. Couldn’t find consistent APN data for Telkomsel, so hopefully it will prove unnecessary.

  12. Prem says:

    hey i bought a samsung galaxy s4 over the weeknd sgh-I337m.
    im not sure which carrier it came from but i am currently using it on wind mobile a aws frequency and its working fine i also have 4g (but im not sure if thats right).
    my question is, i have an update to install and im aware that the device in unlocked. so if i update it will it relock itself?
    not sure where to take this question, please help.

    • Max Lee says:

      No usually it will not lock itself, I have not heard of it. Once it’s unlocked, it stays unlocked for good usually.

  13. Reuben says:

    please can anyone here suggest a site where i can buy the samsung galaxy s4 thats locked to AT&T and unlock it to work on MTN Ghana.

  14. jimmyb says:

    Does this not work anymore? Just got a brand new s4 from att yesterday and cant get past second step service mode menu doesn’t even show up?

  15. hecmig says:

    Same here, I just bought one from ATT I can go to the service stuff using *#0011# but then I hit back and nothing happen, also hit key imput 1 and nothing it just wont go to service menu any clues?
    the phone number its an sgh-i337, baseband i337UCUAMF3 Krenel 3.4.0-812098 the krenel date says Jun 5 2013

    Some help here!

  16. jesse james says:

    does this work on my telus galaxy s4 i337m on the new firmware 4.3.

  17. cristian says:

    hey max i have a att s4 sgh-i337 and i tried typing *#27663368378# but wont work… it works if i type *#197328640# but it will show me a diferent menu and only says the information about the cell and the sim

  18. Dimitry says:

    This worked perfectly for me. I am now trying to sell my phone and wondering whether or not the “unlock” will survive a factory reset. Anybody have any definitive answers? Thanks.

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  20. Remember, unlocking SIM is illegal in the U.S. as of this year, and that is why I cannot make a video tutorial but this method does work well, you can find full step-by-step tutorial at XDA here. However, it is not illegal to unlock your SIM if you are currently in another country other than the U.S. This law should change soon as it only benefits carriers not consumers.

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  21. Matty says:

    This woNt work on 4.3. If you are on 4.2.2 or less, snag Sammy ServiceMode from the play store to make your life easier with getting this working..

  22. Anghel Catalin says:

    I have a Galaxy S4 from ATT and after dialing the numbers *#0011# I hit back and nothing happen, also hit key input 1 and nothing it just wont go to service menu. finally left out and tried a code which i bought from a site, which works perfectly at first attempt.

  23. Bryan Parridge says:

    Hi, I tried the given method but menu options didn’t work as due to samsung’s new update, so utilized to get my unlock code and unlocked in simple steps.

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  26. C. Allen Pinney says:

    Max, I have a tmobile SGH-M919 running android 4.4.4 twrp stock rom build # KTU84P.M919UVUFNK2 Following the steps to “unlock” per the XDA link provided, I cant get into SERVICE MODE with *#27663368378# It simply does nothing. If i hit send it flashes on the screen USSD CODE RUNNING then blacks out and says UNABLE TO PROCESS REQUEST. However if i type in the dialer *#197328640# it takes me to service mode but starts on the DEBUG SCREEN and has different menu selections than shown in the tutoriai. Cant “go back ” any further than where it starts (like a main menu) as if i jumped into a sub menu directly or something. Any direction for me? Thanks

    C. Allen Pinney

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