jerdog · Jul 16, 2012 at 11:00 am

Using the International Galaxy S III on US GSM Carriers

The American mobile carrier market is vastly different from markets in the rest of the world, with the U.S. carrier being the one in charge as opposed to the consumer. The carriers are able to dictate to the manufacturers what they want in their carrier-branded device and the manufacturer largely has to go along in order to get their device to the market. Add to the mix the fact that there are two mobile technologies in the U.S. (CDMA and GSM), and things can become really complicated. This is most evident in devices like the Samsung Galaxy S II (AT&T, T-Mobile and Sprint) where there were four very different devices (2 GSM, 1 GSM/LTE, and 1 CDMA), each with their own specs which differed from the international version, the GT-i9100.

One of the many advantages of purchasing an international device, like the Samsung Galaxy S III GT-i9300, and activating on U.S. GSM networks is that you don’t need to renew your existing contract in order to use it. Another advantage is the savings that can accrue if you choose to use the device on a prepay service outside of the normal constraints of the U.S. carriers. Let’s look at an example of the costs associated with AT&T’s SGS III versus the international version imported to use on that service and on Straight Talk (an MVNO for AT&T). Note that I am using AT&T in this instance because it is currently the only carrier in the U.S. that will take the GT-i9300 natively. Your mileage may vary (YMMV) on the other networks.

  • On AT&T a new service plan with unlimited wireless minutes, unlimited text messaging and 3GB of data will run you $120 per month with a $36 activation fee and a two-year contract, with the AT&T SGS III costing you $200. Over the lifetime of the contract you would have spent $3116 ($120*24+200+36).
  • If you purchase the GT-i9300 for roughly $650 (16GB White version), and then activate that phone with Straight Talk on their comparable plan (they only have 2GB “unlimited” data) for $45 and a $15 activation fee for the SIM card, you will be spending $1745 (650+(45*24)+15) over the same two year contract. But here’s the kicker – you will have NO contract tying you down to either that device or that particular prepay service, which of course places YOU in control instead of the carrier.

That is a savings of $1371 (44%)! Break that up by two years and guess what you’re saving each year? $685 which is more than the initial up-front cost of the international device. How is that NOT good economics? That also does not even taking into account the sale of your existing phone, which can cut down your up-front costs. Heck – I sold my 4-month old GT-i9100 for $350 to purchase my GT-i9300. Of course you could purchase the GT-i9300 and use it on your existing AT&T contract without a renewal, but you really wouldn’t see a cost benefit to that option.

Sure, the AT&T SGS III is LTE whereas the GT-i9300 is HSPA+, but for many that won’t matter. The added speed for some areas of the country most likely isn’t going to add up to $685 of increased productivity, and on Straight Talk you have the exact same coverage and HSPA+ speed as AT&T.

So now that we’ve established the cost benefits of using the international device in the U.S., let’s discuss the logistics of bringing it to a prepay service. Once you get the SIM card for the service all you have to do is plug it in, put the APN in and you’re good to go. No other configuration steps are needed.

One thing that many have noticed, is that when you bring an international device to a U.S. carrier you can potentially lose out on some of the network settings which could enable your device to perform better. One of these benefits is Fast Dormancy. Without going into too much detail, Fast Dormancy (aka FD) is a technology for GSM networks that allows the data connection to go into a dormant state without releasing the device’s IP address and pinging for connection at a reduced timeframe thus theoretically increasing battery life. AT&T does utilize FD in most areas, so again YMMV. You can set the time your device queries the data network from a default of 3 secs while the screen is off to any value above that.

XDA Senior Member cmd512 knew from previous experience that correctly utilizing Fast Dormancy on your international device can give you some positive results, so he started a thread to examine the i9300 and it’s FD settings on AT&T. Here’s what he had to say:

After getting my SGS3, I noticed I was getting consistently slower speeds as well as notable battery drain when only on cellular data. While there were some knuckleheads on here that kept telling me to “use the phone APN” (even though I’m on AT&T’s Medianet and CANNOT use the phone APN), I started digging into the SGS3 Fastdormancy settings as I knew from experience that could impact both download speed and battery life.

When he went digging into the nwk_info.db found in /data/data/ he found that the device had carrier-specific information for all of the carriers in Europe, but nothing for AT&T. After digging into the settings found on ICS ROMs for the AT&T SGS III he was able to duplicate the specific nwk_info.db settings for AT&T’s Fast Dormancy and plugged those in.

Not too long after, I realized that the UK version of the GT-I9300 does not have ANY Fastdormancy data for AT&T medianet. So, I added them in, and now, I’m pulling consistent 5Mbps downloads vs not being able to break 3Mbps previously.

So after seeing the positive results with Fast Dormancy enabled, he put together the exact steps to add in the AT&T settings via SQLite Editor, and put those in the OP of the discussion thread. To get you started with the information already entered, XDA Senior Member ookba provided a nwk_info.db file already configured but with Fast Dormancy turned off. You can install that file and then follow the steps provided by cmd512 to change the lcdonfdtime/lcdofffdtime settings in the dormpolicy table to 0 and 20 respectively, which means that the idle delay for your device when the screen is on is 0 sec (disabled) and 20 sec when the screen is off.

Because of the nature of FD, you may need to disable it if you see secril_fd-interface appear in the list of kernel wakelocks using BetterBatteryStats, and it has a high percentage of wakelock time, i.e. hours as opposed to minutes. To do so, XDA Elite Recognized Developer gokhanmoral decided to make an application he called FastDormancy Toggle for i9300 and placed it in the Google Play store. The application allows you to quickly disable FD without digging into the internals and possible screwing something up.

As with anything you will need to experiment to see what works best for you in your area, along with which specific modem provides the best mix of performance and battery life. But once you do find that sweet spot, I can guarantee your experience with an international device like the GT-i9300 will be much improved, and your wallet might just appreciate you for once.

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jerdog is an editor on XDA-Developers, the largest community for Android users. Jeremy has been an XDA member since 2007, and has been involved in technology in one way or another, dating back to when he was 8 years old and was given his first PC in 1984 - which promptly got formatted. It was a match made in the stars, and he never looked back. He has owned, to date, over 60 mobile devices over the last 15 years and mobile technology just clicks with him. In addition to being a News Editor and OEM Relations Manager, he is a Senior Moderator and member of the Developer and Moderator Committees at XDA. View jerdog's posts and articles here.
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